For Loop Code
int counts = 0;
List<int> count = new List<int>();
List<int> goodnumber = new List<int>();
for (int i = lower; i <= upper; i++)
{
if (!badNumbers.Contains(i)) {
goodnumber.Add(i);
} else {
count.Add(goodnumber.Count);
goodnumber = new List<int>();
}
if (i == upper) {
count.Add(goodnumber.Count);
counts = count.Max();
}
}
return counts;
is there a way to optimize my code above? because the running time for the code above is exceeding in 3 secs. how can I make it 2 or below?
There's a few improvements you can make.
badNumbers should probably be a HashSet<int> which will provide you close to O(1) lookup.
You don't actually care about storing the "good numbers" (you don't use that data), so it would be more efficient to just store how many good numbers you encounter.
Now you just want the max streak size (i.e. max number of consecutive good numbers) you encounter, and you can use Math.Max to compare the last "good" count with the current "good" count and choose the largest.
The code looks like this:
HashSet<int> badNumbers = new HashSet<int>() { 5, 4, 2, 15 };
int counts = 0;
int goodNumberCount = 0;
for (int i = lower; i <= upper; i++)
{
if (!badNumbers.Contains(i)) {
++goodNumberCount;
} else {
counts = Math.Max(counts, goodNumberCount);
goodNumberCount = 0;
}
}
counts = Math.Max(counts, goodNumberCount);
return counts;
Call List.Clear() instead of creating new List inside the loop
Call count.Max() outside the loop
Remove the last if and add this line after the loop count.Add(goodnumber.Count)
int counts = 0;
List<int> count = new List<int>();
List<int> goodnumber = new List<int>();
for (int i = lower; i <= upper; i++)
{
if (!badNumbers.Contains(i)) {
goodnumber.Add(i);
} else {
count.Add(goodnumber.Count);
goodnumber.Clear();
}
}
count.Add(goodnumber.Count);
counts = count.Max();
return counts;
BTW, I don't know what are you trying to achieve with this code.
The correct way to "optimize" your code is to rewrite it. You need to think differently. The problem you have has various different solutions and you are complicating it too much.
You don't need to process the input in one long cycle only. You can pre-process the list somehow, in a way, that would help you. For example sort it.
Another thing that could help you is to have a variable (or variables) in which you are storing some intermediate result. For example running max, min, sum, or previous value of something
Think about how you could solve the problem mathematically. Isn't it just the difference of numbers you are trying to find?
You could sort the list, calculate the difference between each element, bound it by your lower and upper borders. You can either update the running maximum difference during the loop or find the maximum difference from the list of differences.
Here is a general solution:
using System.Collections.Generic;
using System.Linq;
namespace ConsoleApp1
{
class Program
{
static void Main(string[] args)
{
var lower = 1;
var upper = 10;
var elementCount = upper - lower + 1;
var numbers = Enumerable.Range(1, elementCount);
var badNumbers = new HashSet<int> { 5, 4, 2, 15 };
var maxCount = CalculateCounts(numbers, badNumbers).Max();
}
private static IEnumerable<int> CalculateCounts<T>(IEnumerable<T> items, ISet<T> splitOn)
{
var count = 0;
foreach (var item in items)
{
if (!splitOn.Contains(item)) count++;
else
{
yield return count;
count = 0;
}
}
yield return count;
}
}
}
Now, I may get negative points because perhaps somewhere in vast internet there is already an answer to this but I tried to look for it and I simply couldnt find it.
The gist of the problem is that HackerRanks wants you to create an array with a size decided by the user, then have the user add its values (integers) and finally have the program sum its values.
There are plenty of ways to do it and I already know how to but my problem is that I just can't understand Hackerrank's code sample in C# it gave me. I commented the parts I don't understand, which is most of it:
static int simpleArraySum(int n, int[] ar) {
// Complete this function
int sum = 0;
foreach( var item in ar){
sum += item;
}
return sum;
}
static void Main(String[] args) {
//I know what this does
int n = Convert.ToInt32(Console.ReadLine());
//I am lost here, just why create a string array and add the split method?
string[] ar_temp = Console.ReadLine().Split(' ');
//I dont understand here neither, what is it converting? What is the parse for?
int[] ar = Array.ConvertAll(ar_temp,Int32.Parse);
//Why send the n when all you need is the array itself?
int result = simpleArraySum(n, ar);
Console.WriteLine(result);
}
I know some people hate HackerRank, and honestly, I do too but it does gives me some nice ways to test my limited skills in coding with c# and testing my logic. So, if there are better sites that helps you test your logic as a CS please share them with me.
Here is the code I made to solve this problem in Visual Studio but for some stupid reason Hackerrank wont accept it unless I make custom inputs:
//This code can be potentially shorter using the code commented further below.
//For practice's sake, it was made longer.
static int simpleArraySum(int[] arr_temp)
{
int total = 0;
foreach (var item in arr_temp)
{
total += item;
}
return total;
}
static void Main(String[] args)
{
int n = Convert.ToInt32(Console.ReadLine());
int[] arr_temp = new int[n];
for (int i = 0; i < n; i++)
{
arr_temp[i] = Convert.ToInt32(Console.ReadLine());
}
int result = simpleArraySum(arr_temp);
//int result = arr_temp.Sum();
Console.WriteLine(result);
Console.ReadLine();
}
You need to convert to string array since if you're on the main method, all it gets are string values from the argument list. To get the sum then you need to convert the string into a usable number / integer.
I agree that it doesn't make sense to send the first argument n in simpleArraySum because n is simply unused.
as for the part int[] ar = Array.ConvertAll(ar_temp,Int32.Parse); it simply tries to take in all the integers into the array. It is also risky because if you accidentally pass in a string then it will throw an error i.e. pass in "3 4 1 f" <- f will throw an exception, unless this is the desired behaviour.
Personally I think the main method should not be interested in getting involved too much with the data, the heavy lifting should be done in the methods. The better version perhaps would be to modify simpleArraySum and refactor that line in like:
static int simpleArraySum(string input)
{
String[] fields = input.Split(null);
List<int> vals = new List<int>();
foreach (string i in fields)
{
var j = 0;
if (Int32.TryParse(i, out j)) vals.Add(j);
}
int sum = 0;
foreach (var item in vals)
{
sum += item;
}
return sum;
}
I introduced the use of generic list because it's more readable if not cleaner, although the use of List might look overkill to some programmers and might not be as light weight as just using an array, hence on the other hand you can easily stick to using arrays except that it needs to be initialized with the length i.e. int[] vals = new int[fields.Length]; Roughly:
static int simpleArraySum(string input)
{
String[] fields = input.Split(null);
int[] vals = new int[fields.Length];
for (int i = 0; i < fields.Length; i++)
{
var j = 0;
if (Int32.TryParse(fields[i], out j)) vals[i] = j;
}
int sum = 0;
foreach (var item in vals)
{
sum += item;
}
return sum;
}
here my code i hope that helps
static int simpleArraySum(int[] ar,int count) {
if (count > 0 && count <= 10000)
{
if (count == ar.Length)
{
if (!ar.Any(item => (item < 0 || item >= 10000)))
{
return ar.Sum();
}
}
}
return 0;
}
and in main
int arCount = Convert.ToInt32(Console.ReadLine());
int[] arr = Array.ConvertAll(Console.ReadLine().Split(' '), arTemp => Convert.ToInt32(arTemp));
int result = simpleArraySum(arr, arCount);
Console.WriteLine(result);
since Array.ConvertAll() takes a string and convert it to one type array
int or float for example
For users still looking for a 100% C# solution: In above mentioned coding websites do not modify the main function. The aim of the test is to complete the function via the online complier.
using System.Linq;
public static int simpleArraySum(List<int> ar)
{
int sum = ar.Sum();
return sum;
}
So I'm working on an MVC view model that will tell a user if a given integer input is a Happy Number or not. As stated, the final code will sit in an MVC view model, but in the meantime, I've been checking the logic by debugging the code as a separate console app. I've got the console app working, but when I migrate the code back to the view model and then debug in the full application, literally nothing happens and IIS eventually times out the request. My view and controller implementations look solid (I'm leaving out that code for now), so I think I'm screwing up the logic in my actual model. Thoughts?
The code explained in further detail:
I'm new to OO programming, so for the sake of my own comprehension, I have split up the program into to two separate functions (Yes, I am aware this is bad practice, but it's homework). The first function (see below), which I've called "sumPowered", takes an integer input, separates the individual digits into an array, squares the individual digits, and returns the sum of the squared digits. Next, I have created a validation function called "isHappy" in which I call the preceding sumPowered function, pass through the parameters, generate a result array, and compare them to the happy number conditions.
To provide a clear outline, the first block of code below is the working code as it appears in my console app. The second block demonstrates how the code appears in the view model (doesn't work).
EDIT: I should have clarified that I am not producing any build errors or errors in the console view of Chrome's property inspector when I run the MVC code, yet the function did not work. I have since found a fix (answer post pending).
CONSOLE APP
//CONSOLE APP
namespace MoreCSharpPractice
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Enter a number");
int number = Convert.ToInt32(Console.ReadLine());
isHappy(number);
}
public static int sumPowered(int num, int pow)
{
int sum = 0;
List<int> numsL = new List<int>();
while (num > 0)
{
numsL.Add(num % 10);
num = num / 10;
}
int[] nums = numsL.ToArray();
for (int a = 0; a < nums.Length; a++)
{
sum += Convert.ToInt32(Math.Pow(Convert.ToDouble(nums[a]), Convert.ToDouble(pow)));
}
return sum;
}
//HAPPY NUMBER
//return true if 'number' is a happy number.
private static void isHappy(int number)
{
List<int> sumArray = new List<int>();
bool running = true;
while (running)
{
int result = sumPowered(number, 2);
if (result == 1)
{
running = false;
Console.WriteLine("Is a Happy Number!");
}
else if (sumArray.Contains(result))
{
running = false;
//return false;
Console.WriteLine("Is not a Happy Number");
}
number = result;
sumArray.Add(result);
}
//return true;
Console.ReadKey();
}
}
}
MVC CODE
//VIEW MODEL CODE: SUM POWERED FUNCTION
public static int sumPowered(int num, int pow)
{
int sum = 0;
List<int> numsL = new List<int>();
while (num > 0)
{
numsL.Add(num % 10);
num = num / 10;
}
int[] nums = numsL.ToArray();
for (int i = 0; i < nums.Length; i++)
{
sum += Convert.ToInt32(Math.Pow(Convert.ToDouble(nums[i]), Convert.ToDouble(pow)));
}
return sum;
}
//VIEW MODEL CODE: HAPPY NUMBER FUNCTION
//return true if 'number' is a happy number.
private static bool isHappy(int number)
{
List<int> sumArray = new List<int>();
while (true)
{
int result = sumPowered(number, 2);
if (result == 1)
{
return true;
}
else if (sumArray.Contains(result))
{
return false;
}
number = result;
sumArray.Add(result);
}
}
Determined that this wasn't a logic error but instead a performance issue while running debug. By changing the data type of variable sumArray in my isHappy() function from a List to a HashSet, I was able to run through the function without having to iterate through an entire list when invoking else if (sumArray.Contains(result)).
//HAPPY NUMBER
//return true if 'number' is a happy number.
private static bool isHappy(int number)
{
HashSet<int> sumArray = new HashSet<int>();
while (true)
{
int result = sumPowered(number, 2);
if (result == 1)
{
return true;
}
else if (sumArray.Contains(result))
{
return false;
}
number = result;
sumArray.Add(result);
}
}
Hi i am working on Grade Calculation. My problem here is if the length of string array is longer that int array it works skipping the last 2 grades.
ex:
int[] unit = new int[] {1,-3,3,4};
string[] letter_grade = new string[] {"A", "B","B","W","D","F"};
but if length of int array longer than that of string array its not working its throwing error Index was outside the bounds of the array.
int[] unit = new int[] {1,-3,3,4,5,6,7};
string[] letter_grade = new string[] {"A", "B","B"};
so my question how do i make it work for both??
int length = unit.Length;
int no_units = length;
double totalGrade_Points = 0.0;
int totalno_units = 0;
totalGPA = 0;
for (int i = 0; i < unit.Length; i++)
{
entrygot = findGpaListentry(letter_grade[i]); //Index was outside the bounds of the array.
if (entrygot != null)
{
//some code calculation
}
}
For array indexing you must have starting and stopping condition defined very well. For accessing two arrays either they must be equal or they are compared under certain valid conditions. Have a look at this:
for(int i=0;i<unit.length;i++){
entrygot = findGpaListentry(letter_grade[i]);// only if letter_grade is valid under all values of i i.e unit.length
}
// either you have to check as if;
if(lenght_of_letter_grade < i-1)
//then access
entrygot = findGpaListentry(letter_grade[i]);
You can't just check if the array item is null, because you would be out of the bounds of the array and you will get an exception before the null check occurs.
I would check the length of the array on each iteration...
for (int i = 0; i < unit.Length; i++)
{
if (currentArray.Length < i - 1) { break; }
// other code...
}
I think in your case, the number of elements will never be large hence performance wont be an issue. So I think you should be using a List instead of an array. With an array you will have to be insert checks each time some logic changes or you add other functionalities.
foreach loop is best for your scenerio.
foreach (string s in letter_grade)
{
entrygot = findGpaListentry(s);
if (entrygot != null)
{
//some code calculation
}
}
Probably a really simple one this - I'm starting out with C# and need to add values to an array, for example:
int[] terms;
for(int runs = 0; runs < 400; runs++)
{
terms[] = runs;
}
For those who have used PHP, here's what I'm trying to do in C#:
$arr = array();
for ($i = 0; $i < 10; $i++) {
$arr[] = $i;
}
You can do this way -
int[] terms = new int[400];
for (int runs = 0; runs < 400; runs++)
{
terms[runs] = value;
}
Alternatively, you can use Lists - the advantage with lists being, you don't need to know the array size when instantiating the list.
List<int> termsList = new List<int>();
for (int runs = 0; runs < 400; runs++)
{
termsList.Add(value);
}
// You can convert it back to an array if you would like to
int[] terms = termsList.ToArray();
Edit: a) for loops on List<T> are a bit more than 2 times cheaper than foreach loops on List<T>, b) Looping on array is around 2 times cheaper than looping on List<T>, c) looping on array using for is 5 times cheaper than looping on List<T> using foreach (which most of us do).
Using Linq's method Concat makes this simple
int[] array = new int[] { 3, 4 };
array = array.Concat(new int[] { 2 }).ToArray();
result
3,4,2
If you're writing in C# 3, you can do it with a one-liner:
int[] terms = Enumerable.Range(0, 400).ToArray();
This code snippet assumes that you have a using directive for System.Linq at the top of your file.
On the other hand, if you're looking for something that can be dynamically resized, as it appears is the case for PHP (I've never actually learned it), then you may want to use a List instead of an int[]. Here's what that code would look like:
List<int> terms = Enumerable.Range(0, 400).ToList();
Note, however, that you cannot simply add a 401st element by setting terms[400] to a value. You'd instead need to call Add() like this:
terms.Add(1337);
By 2019 you can use Append, Prepend using LinQ in just one line
using System.Linq;
and then in NET 6.0:
terms = terms.Append(21);
or versions lower than NET 6.0
terms = terms.Append(21).ToArray();
Answers on how to do it using an array are provided here.
However, C# has a very handy thing called System.Collections
Collections are fancy alternatives to using an array, though many of them use an array internally.
For example, C# has a collection called List that functions very similar to the PHP array.
using System.Collections.Generic;
// Create a List, and it can only contain integers.
List<int> list = new List<int>();
for (int i = 0; i < 400; i++)
{
list.Add(i);
}
Using a List as an intermediary is the easiest way, as others have described, but since your input is an array and you don't just want to keep the data in a List, I presume you might be concerned about performance.
The most efficient method is likely allocating a new array and then using Array.Copy or Array.CopyTo. This is not hard if you just want to add an item to the end of the list:
public static T[] Add<T>(this T[] target, T item)
{
if (target == null)
{
//TODO: Return null or throw ArgumentNullException;
}
T[] result = new T[target.Length + 1];
target.CopyTo(result, 0);
result[target.Length] = item;
return result;
}
I can also post code for an Insert extension method that takes a destination index as input, if desired. It's a little more complicated and uses the static method Array.Copy 1-2 times.
Based on the answer of Thracx (I don't have enough points to answer):
public static T[] Add<T>(this T[] target, params T[] items)
{
// Validate the parameters
if (target == null) {
target = new T[] { };
}
if (items== null) {
items = new T[] { };
}
// Join the arrays
T[] result = new T[target.Length + items.Length];
target.CopyTo(result, 0);
items.CopyTo(result, target.Length);
return result;
}
This allows to add more than just one item to the array, or just pass an array as a parameter to join two arrays.
You have to allocate the array first:
int [] terms = new int[400]; // allocate an array of 400 ints
for(int runs = 0; runs < terms.Length; runs++) // Use Length property rather than the 400 magic number again
{
terms[runs] = value;
}
int ArraySize = 400;
int[] terms = new int[ArraySize];
for(int runs = 0; runs < ArraySize; runs++)
{
terms[runs] = runs;
}
That would be how I'd code it.
C# arrays are fixed length and always indexed. Go with Motti's solution:
int [] terms = new int[400];
for(int runs = 0; runs < 400; runs++)
{
terms[runs] = value;
}
Note that this array is a dense array, a contiguous block of 400 bytes where you can drop things. If you want a dynamically sized array, use a List<int>.
List<int> terms = new List<int>();
for(int runs = 0; runs < 400; runs ++)
{
terms.Add(runs);
}
Neither int[] nor List<int> is an associative array -- that would be a Dictionary<> in C#. Both arrays and lists are dense.
You can't just add an element to an array easily. You can set the element at a given position as fallen888 outlined, but I recommend to use a List<int> or a Collection<int> instead, and use ToArray() if you need it converted into an array.
If you really need an array the following is probly the simplest:
using System.Collections.Generic;
// Create a List, and it can only contain integers.
List<int> list = new List<int>();
for (int i = 0; i < 400; i++)
{
list.Add(i);
}
int [] terms = list.ToArray();
one approach is to fill an array via LINQ
if you want to fill an array with one element
you can simply write
string[] arrayToBeFilled;
arrayToBeFilled= arrayToBeFilled.Append("str").ToArray();
furthermore, If you want to fill an array with multiple elements you can use the
previous code in a loop
//the array you want to fill values in
string[] arrayToBeFilled;
//list of values that you want to fill inside an array
List<string> listToFill = new List<string> { "a1", "a2", "a3" };
//looping through list to start filling the array
foreach (string str in listToFill){
// here are the LINQ extensions
arrayToBeFilled= arrayToBeFilled.Append(str).ToArray();
}
Array Push Example
public void ArrayPush<T>(ref T[] table, object value)
{
Array.Resize(ref table, table.Length + 1); // Resizing the array for the cloned length (+-) (+1)
table.SetValue(value, table.Length - 1); // Setting the value for the new element
}
int[] terms = new int[10]; //create 10 empty index in array terms
//fill value = 400 for every index (run) in the array
//terms.Length is the total length of the array, it is equal to 10 in this case
for (int run = 0; run < terms.Length; run++)
{
terms[run] = 400;
}
//print value from each of the index
for (int run = 0; run < terms.Length; run++)
{
Console.WriteLine("Value in index {0}:\t{1}",run, terms[run]);
}
Console.ReadLine();
/*Output：
Value in index 0: 400
Value in index 1: 400
Value in index 2: 400
Value in index 3: 400
Value in index 4: 400
Value in index 5: 400
Value in index 6: 400
Value in index 7: 400
Value in index 8: 400
Value in index 9: 400
*/
If you don't know the size of the Array or already have an existing array that you are adding to. You can go about this in two ways. The first is using a generic List<T>:
To do this you will want convert the array to a var termsList = terms.ToList(); and use the Add method. Then when done use the var terms = termsList.ToArray(); method to convert back to an array.
var terms = default(int[]);
var termsList = terms == null ? new List<int>() : terms.ToList();
for(var i = 0; i < 400; i++)
termsList.Add(i);
terms = termsList.ToArray();
The second way is resizing the current array:
var terms = default(int[]);
for(var i = 0; i < 400; i++)
{
if(terms == null)
terms = new int[1];
else
Array.Resize<int>(ref terms, terms.Length + 1);
terms[terms.Length - 1] = i;
}
If you are using .NET 3.5 Array.Add(...);
Both of these will allow you to do it dynamically. If you will be adding lots of items then just use a List<T>. If it's just a couple of items then it will have better performance resizing the array. This is because you take more of a hit for creating the List<T> object.
Times in ticks:
3 items
Array Resize Time: 6
List Add Time: 16
400 items
Array Resize Time: 305
List Add Time: 20
I will add this for a another variant. I prefer this type of functional coding lines more.
Enumerable.Range(0, 400).Select(x => x).ToArray();
You can't do this directly. However, you can use Linq to do this:
List<int> termsLst=new List<int>();
for (int runs = 0; runs < 400; runs++)
{
termsLst.Add(runs);
}
int[] terms = termsLst.ToArray();
If the array terms wasn't empty in the beginning, you can convert it to List first then do your stuf. Like:
List<int> termsLst = terms.ToList();
for (int runs = 0; runs < 400; runs++)
{
termsLst.Add(runs);
}
terms = termsLst.ToArray();
Note: don't miss adding 'using System.Linq;' at the begaining of the file.
This seems like a lot less trouble to me:
var usageList = usageArray.ToList();
usageList.Add("newstuff");
usageArray = usageList.ToArray();
Just a different approach:
int runs = 0;
bool batting = true;
string scorecard;
while (batting = runs < 400)
scorecard += "!" + runs++;
return scorecard.Split("!");
int[] terms = new int[400];
for(int runs = 0; runs < 400; runs++)
{
terms[runs] = value;
}
static void Main(string[] args)
{
int[] arrayname = new int[5];/*arrayname is an array of 5 integer [5] mean in array [0],[1],[2],[3],[4],[5] because array starts with zero*/
int i, j;
/*initialize elements of array arrayname*/
for (i = 0; i < 5; i++)
{
arrayname[i] = i + 100;
}
/*output each array element value*/
for (j = 0; j < 5; j++)
{
Console.WriteLine("Element and output value [{0}]={1}",j,arrayname[j]);
}
Console.ReadKey();/*Obtains the next character or function key pressed by the user.
The pressed key is displayed in the console window.*/
}
/*arrayname is an array of 5 integer*/
int[] arrayname = new int[5];
int i, j;
/*initialize elements of array arrayname*/
for (i = 0; i < 5; i++)
{
arrayname[i] = i + 100;
}
To add the list values to string array using C# without using ToArray() method
List<string> list = new List<string>();
list.Add("one");
list.Add("two");
list.Add("three");
list.Add("four");
list.Add("five");
string[] values = new string[list.Count];//assigning the count for array
for(int i=0;i<list.Count;i++)
{
values[i] = list[i].ToString();
}
Output of the value array contains:
one
two
three
four
five
You can do this is with a list. here is how
List<string> info = new List<string>();
info.Add("finally worked");
and if you need to return this array do
return info.ToArray();
Here is one way how to deal with adding new numbers and strings to Array:
int[] ids = new int[10];
ids[0] = 1;
string[] names = new string[10];
do
{
for (int i = 0; i < names.Length; i++)
{
Console.WriteLine("Enter Name");
names[i] = Convert.ToString(Console.ReadLine());
Console.WriteLine($"The Name is: {names[i]}");
Console.WriteLine($"the index of name is: {i}");
Console.WriteLine("Enter ID");
ids[i] = Convert.ToInt32(Console.ReadLine());
Console.WriteLine($"The number is: {ids[i]}");
Console.WriteLine($"the index is: {i}");
}
} while (names.Length <= 10);