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I solved this codility test with the following code:
private static int lesson2_1(int[] A) {
if (!Isvalid(A))
{
return -1;
}
List<int> d = A.Distinct().ToList();
foreach (var item in d)
{
var q = from one in A where one == item select one;
if (q.Count() == 1)
{
return item;
}
}
return -1;
}
private static bool Isvalid(int[] a)
{
if (a.Length == 0)
{
return false;
}
return true;
}
These are the results:
I do not know how to approach this, since I have not learned yet about complexity. Can someone please guide me to the right approach to this issue?
Many thanks
My advice - don't reinvent the wheel. .Net has a lot built into it. Chances are unless you have specialist requirements Microsoft will be able to implement it better than you. The following gets a 100% score:
using System;
using System.Linq;
class Solution {
public int solution(int[] A) {
return A.GroupBy(a => a).First(a => a.Count() %2 == 1).Key;
}
}
There are a few issues with your solution.
1) You aren't following the test spec. It states
all but one of the values in A occur an even number of times.
That means that the number you are looking for could occur, 3,5,7,etc. times - you are just checking for 1.
2) The time complexity of your solution is poor. You are looping through every item and doing a search for each item within every loop. This isn't necessary if you think about it. You will have to go through every item in the list but if you process it as you go along you effectively only have to go through each item once and then the buckets of each item once.
Related
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Can anyone assist on below WPF GUI how to convert to Linq due to low performance:
foreach (Grid b in main_grid.Children)
{
foreach (Control s in b.Children)
{
if (s.GetType() == typeof(Button))
{
if (s.Tag.ToString() == message)
{
if (status == "OIRS_INUSE")
{
s.Background = Brushes.Orange;
}
else
{
s.Background = defaultBackground;
}
}
}
}
}
First, you are asking the wrong question. Linq doesn't help.
One way to speed up this loop is to reduce the workload of its bottleneck:
foreach (Grid b in main_grid.Children)
{
foreach (Control s in b.Children)
{
if (s.SomeEnumValue == SomeEnum.Value)
{
s.Background = Brushes.Orange;
}
else
{
s.Background = defaultBackground;
}
}
}
First comparison if (s.GetType() == typeof(Button)) is costly:
for 100 million calls:
typeof(Test): 2756ms
TestType (field): 1175ms
test.GetType(): 3734ms
you'll have more than 5 times slower than a simple field comparison.
Second comparison if (s.Tag.ToString() == message) and third comparison status == "OIRS_INUSE" are costly
Moreover, the second comparison contains a ToString method which has its own cost.
So get rid of all these expensive comparisons and replace them with a simple field comparison such as an enum which is cheap.
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I am using C# with the Selenium Webdriver. I want to break the loop if the 'if' condition isn't met. My code is below. If the 'if' condition is met I want to continue the loop until it isn't.
for (int i = 0; i < Numara.Items.Count; i++)
{
driveri.Navigate().GoToUrl("https://web.whatsapp.com/send?phone=" + Numara.Items[i].ToString() + "&text=");
Thread.Sleep(3000);
Actions act = new Actions(driveri);
Thread.Sleep(500);
IReadOnlyCollection<IWebElement> rows = driveri.FindElements(By.XPath("//*[#id=\"app\"]/div/span[3]/div/div/div/div/div/div/div[2]/div"));
if (rows == null)
{
...continuation
}
else
{
...if there is an error
rows.ElementAt(0).Click();
}
}
}
This is what you are asking for
if (rows == null)
{
continue;
}
else
{
rows.ElementAt(0).Click();
break;
}
However it'd be better code practice and more efficient to use a while loop implementation instead;
IReadOnlyCollection<IWebElement> rows = null;
bool rowsFound = false;
while (!rowsFound)
{
rows = driveri.FindElements(By.XPath("//*[#id=\"app\"]/div/span[3]/div/div/div/div/div/div/div[2]/div"));
if(rows!=null)
{
rowsFound = true;
}
}
rows.ElementAt(0).Click();
On an unrelated topic, it's also bad practice to be using Thread.Sleep(), unless absolutely necessary. Most, if not all the time you will want to use WebDriverWait implementation. You can find out more about that here: https://seleniumhq.github.io/selenium/docs/api/dotnet/html/T_OpenQA_Selenium_Support_UI_WebDriverWait.htm
The OP's issue description is quite confusing
I want to use selenium in c # to close the loop if it fails.
If the error comes out, I want to click on the link and continue the
loop.
If you want to end the loop immediately after encountering an error, use break.
Using continue on the other hand will skip the remaining statements and will go to the next iteration of your loop.
else
{
...if there is an error
rows.ElementAt(0).Click();
break;
}
Away from the topic though , I just noticed your Absolute XPATH usage. Using absolute is not really advisable, be better to use relative-concise and short xpath. An update to webapp, will surely break your xpath's of your script.
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i want my if loop to do nothing when the conditions that i gave it are there
i'm new to C# and winform so i searched the internet but didnt find an answer that seems to work and right now i have no idea what to do.
,Mo
screenshot of the loop
If I understand your question correctly, you want to "cancel" all operations in the current method, right? You can use return; to do that:
if(value2 == null) return;
There is just one other thing wrong with your code: value2 will never be null.
decimal value2;
if(!decimal.TryParse(result[1], out value2)) return;
should work a lot better ;)
I can't see any loop in the code provided. You want to change Parse to TryParse and use return in order to return from the method (== do nothing):
public void button14_Click(Object sender, EventArgs e) {
string[] result = input1.Text.Split(Oprator);
//TODO: it may appear, that you want TryParse here as well
decimal value1 = decimal.Parse(result[0]);
decimal value2;
// If you have too few items, and thus you have no "value2" - do nothing
if (result.Length < 2)
return;
// Try parse result[1] to decimal; if parse fails (e.g. result[1] == "zzz") - do nothing
if (!decimal.TryParse(result[1], out value2))
return;
// you have value1, value2, Oprator; put required logic here
switch (Oprator) {
...
}
}
Have you thought about a "While" loop?
int n = 1;
while (n < 6)
{
Console.WriteLine("Current value of n is {0}", n);
n++;
}
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Must be a simple question, and I'm again close to a nervous breakdown because I can't find it:
I have a multimensional List that I defined as an own class (Id, Title, Desc, Start, Length, URL) and that I filled in one function
hyperlist.Add(
new ListElement
{
Id = n,
Title = title,
Desc = desc,
Start = OffsetTotal,
Length = TagLength,
URL = LinkURL
});
I pass it to another function where I have to loop through it and compare each entry of the list to a parameter.
void BuildGList(List<ListElement> LinkList)
{
int startIndex = 5;
foreach (int Id in LinkList)
{
if(startIndex < Start)
{
....
}
}
}
I don't see how to address each single column and googling it I get the impression that nobody uses lists to do what I want here.
-update-
I am asked to clarify my question. Lucky enough it had been clear to the ones that answered it: I didn't know how to refer to a special parameter in a List. Now I know that you can do it with item.parameter.I'm really grateful for the help received in Stackoverflow but sometimes I get the impression that many of you experienced coders have little empathy and understanding for the problems a beginner faces and the effort it takes to google through a jungle of posts. Especially if you are a beginner and therefore sometimes miss the correct keywords. On this one I was busy for an hour and close to a breakdown as I knew I was catching really simple. If you know it then it's always easy. Cheers
You can use foreach like this:
foreach (ListElement item in LinkList)
{
if (item.Length < startIndex)
{
//Do something
}
}
You can filter the list using Linq e.g. to return an IEnumerable as the subset you could do:
private IEnumerable<ListElement> BuildGList(List<ListElement> linkList)
{
int startIndex = 5;
return linkList.Where(element => startIndex < element.Start);
}
You can use takewhile with a foreach if you want to use the list index:
foreach(var item in LinkList.TakeWhile((item, index) => index < startIndex))
{
//enter your code here
}
Also, if you want to compare with a element value inside the list, you can use where with the foreach:
foreach(var item in LinkList.Where(item => item.Start < startIndex))
{
//enter your code here
}
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I am going Round-Robin Algorithm. I am doing in that everything must be created dynamically and Randomly. When I want to go second time to check if I have and value the is more than 0 in the checking point it says that "The given key was not present in the dictionary". How can I Fix this problem.
private int GetNextNodeToProcesssRandom()
{
int NextNodeIndex = -1;
if (NextNodeToProcess >= this.waytosave.Count)
{
NextNodeToProcess = 0;
}
for (int i = NextNodeToProcess; i < this.waytosave.Count; i++)
{
if (this.waytosave[i] > 0)//the problem appears here when the cod goes for the second time.
{
NextNodeIndex = i;
break;
}
}
NextNodeToProcess++;
return NextNodeIndex;
}
It is somehow unclear what is your exact goal. However if you want to loop through a Dict you can use:
foreach(KeyValuePair<TKey, TValue> entry in MyDict)
{
// do something with entry.Value or entry.Key
}
Now if you want to add a check in your program you can try:
if (MyDict.ContainsKey(this.waytosave[i]))
///continue execution...
A look here might help you