Develop Reference

How to rearrange a string so no adjent letters are the same

I am trying to rearrange a given string, so no two adjacent letters are the same.
For that I'm thinking to count every distinct letter's occurence, and then rearrange the string the characters occurence number
example:
Input: AABAABBC
Output: AAAABBBC
and after that spliting it in 2 different strings
AAAA BBBC
and then trying to get the final result.
My question is how do I rearrange the string without using Linq?
Here is my code so far:
private static string GetDistinctChars(string text)
{
string result = "";
foreach (char c in text)
{
if (!result.Contains(c))
{
result += c;
}
}
return result;
}
private static double GetCharOccurrence(string text, char charToCount)
{
int count = 0;
foreach (char c in text)
{
if (c == charToCount)
{
count++;
}
}
return count;
}

You can do it like that:
string example = "AABBAACDCAA";
var orderList = example.OrderBy(x => x).ToList();
List<string> letters = new List<string>();
string temp = string.Empty;
for(int i = 0; i < orderList.Count; i++)
{
temp += orderList[i];
if (i + 1 == orderList.Count)
{
letters.Add(temp);
break;
}
if(orderList[i] != orderList[i + 1])
{
letters.Add(temp);
temp = string.Empty;
}
}
string result = String.Join(" ", letters);
Console.WriteLine(result);
If you don't want to use Linq Order by method, you should implement sorting algorithm like this:
static char[] SortArray(char[] array)
{
int length = array.Length;
char temp = array[0];
for (int i = 0; i < length; i++)
{
for (int j = i + 1; j < length; j++)
{
if (array[i] > array[j])
{
temp = array[i];
array[i] = array[j];
array[j] = temp;
}
}
}
return array;
}
and use it in your program:
string example = "AABBAACDCAA";
var orderList = SortArray(example.ToCharArray());
List<string> letters = new List<string>();
string temp = string.Empty;
for(int i = 0; i < orderList.Length; i++)
{
temp += orderList[i];
if (i + 1 == orderList.Length)
{
letters.Add(temp);
break;
}
if(orderList[i] != orderList[i + 1])
{
letters.Add(temp);
temp = string.Empty;
}
}
string result = String.Join(" ", letters);
Console.WriteLine(result);
alternativly, if you don't want to use list anymore, you can operate only on strigns:
string example = "AABBAACDCAA";
var orderList = SortArray(example.ToCharArray());
string lettersString = string.Empty;
for (int i = 0; i < orderList.Length; i++)
{
lettersString += orderList[i];
if (i + 1 == orderList.Length)
break;
if (orderList[i] != orderList[i + 1])
lettersString += " ";
}
Console.WriteLine(lettersString);

You can find your problem on LeetCode, it's a problem #767.
My algorithm is
If we have too many of same characters, we can't solve the problem (e.g. "aaaaaabc")
If solution exists, we can sort characters aababc -> aaabbc and then take item by item from the beginning and from the center:
For instance:
aababc -> aaabbc (ordered by frequency: a appears 3 time, b - 2, c - 1)
then
aaabbc => ab
^ ^
take these
aaabbc => abab
^ ^
take these
aaabbc => ababac <- final answer
^ ^
take these
Code:
using System.Linq;
using System.Text;
...
public static string ReorganizeString(string s) {
int count = s.GroupBy(c => c).Max(g => g.Count());
// One of the item is too frequent, no solutions
if (count > (s.Length + 1) / 2)
return "";
string st = string.Concat(s
.GroupBy(c => c)
.OrderByDescending(g => g.Count())
.ThenBy(g => g.Key) // not required, just for aesthetic
.SelectMany(c => c));
StringBuilder sb = new StringBuilder(s.Length);
for (int i = 0; i < s.Length / 2; ++i) {
sb.Append(st[i]);
sb.Append(st[(st.Length + 1) / 2 + i]);
}
// Middle character
if (s.Length % 2 != 0)
sb.Append(st[st.Length / 2]);
return sb.ToString();
}
Demo:
string value = "AABAABBC";
Console.Write(ReorganizeString(value));
Output:
ABABABAC
Fiddle it yourself.
Edit: If StringBuilder (as well as System.Text) is really forbidden, we can use string, which, however, slows down the routine:
using System.Linq;
...
public static string ReorganizeString(string s) {
int count = s.GroupBy(c => c).Max(g => g.Count());
// One of the item is too frequent, no solutions
if (count > (s.Length + 1) / 2)
return "";
string st = string.Concat(s
.GroupBy(c => c)
.OrderByDescending(g => g.Count())
.ThenBy(g => g.Key) // not required, just for aesthetic
.SelectMany(c => c));
string result = "";
for (int i = 0; i < s.Length / 2; ++i) {
result += st[i];
result += st[(st.Length + 1) / 2 + i];
}
// Middle character
if (s.Length % 2 != 0)
result += st[st.Length / 2];
return result;
}

C# merge lines of strings into groups of 3 at a time

I have a string like this (including newlines)
A2,
10.22,
-57,
A,
10.23,
-68,
A2,
10.24,
-60,
LB,
10.25,
-62,
I am trying to make this string to look like this:
A2,10.22,-57,
A,10.23,-68,
A2,10.24,-60,
LB,10.25,-62,
I need to join string in every 3 line i have tried :
int numLines = a.Split('\n').Length;
for (int i = 0; i < numLines; i += 3)
{
richTextBox1.Text = a.Replace("\n", "");
}
But it is not working for me. Please help me out

You can also approach this with LINQ, by using the index overload of .Select to retain a running count of the line numbers, and then to group them into groups of 3 - I've used integer division to Floor the line index, 3 at a time, but there are likely other suitable ways.
var groups = values.Select((s, idx) => (Index: idx / 3, Value: s))
.GroupBy(x => x.Index);
Where each item in the groups above will be IEnumerable<(Index, Value)>.
You'll also need to be wary of newlines - these may be \r\n in Windows, not just the \n you've indicated.
Here's an example:
var a =
#"A2,
10.22,
-57,
A,
10.23,
-68,
A2,
10.24,
-60,
LB,
10.25,
-62,";
var values = a.Split(new[] { "\r\n", "\r", "\n" }, StringSplitOptions.None);
var groups = values.Select((s, idx) => (Index: idx / 3, Value: s))
.GroupBy(x => x.Index);
foreach (var grp in groups)
{
Console.WriteLine(string.Join("", grp.Select(x => x.Value)));
}
Since you've already got commas at the end of each string (including the last one), there's no need to add another separator.
Output:
A2,10.22,-57,
A,10.23,-68,
A2,10.24,-60,
LB,10.25,-62,

Why not use the array that the split gives you instead?
var newArr = a.Split('\n');
for (int i = 0; i < newArr.Length; i += 3)
{
richTextBox1.Text = newArr[i] + newArr[i + 1] + newArr[i + 2];
}
Just don't forget to check the length of the arrays so that you don't get a IndexOutOfRange Exception.

I'm assuming that the input is actually coming from a file here.
var file = //file path
var sb = new StringBuilder();
var lineNum = 1;
var output = string.Empty;
using (var reader = new StreamReader(file))
{
while (!reader.EndOfStream)
{
var line = reader.ReadLine();
if (lineNum % 3 == 0)
{
output += sb.ToString() + "\n";
sb.Clear();
}
else
sb.Append(line);
lineNum++;
}
}
richTextBox1.Text = output;

Try this solution which is a combination of linq and for loop
var result = "";
var items = yourInputString.Split('\n');
for(var i=0; i<items.Count();i=i+3)
{
result += string.Join(",",items.Skip(i).Take(3))+"\n";
}

static void Main(string[] args)
{
var Lines = System.IO.File.ReadAllLines("input.txt");
var Result = new StringBuilder();
var SB = new StringBuilder();
for (var i = 0; i < Lines.Length; i++)
{
SB.Append(Lines[i]);
if ((i+1) % 3 == 0)
{
Result.Append($"{SB.ToString()}{Environment.NewLine}");
SB.Clear();
}
}
System.IO.File.WriteAllText("output.txt", Result.ToString());
}

Try to use Aggregate function
var outPutList = data.Replace("\r", string.Empty).Replace("\n", string.Empty).Split(",").Aggregate(new StringBuilder(""), (x, y) =>
{
if (double.TryParse(y, out double parsedValue))
x.Append(" " + parsedValue);
else
{
x.Append(Environment.NewLine);
x.Append(y.Trim());
}
return x;
});
richTextBox1.Text = outPutList.ToString();
Here is the output

try this works
private void button1_Click(object sender, EventArgs e)
{
//put your string in a textxbox with multiline property set to true
string[] s = textBox1.Text.Replace("\r", "").Replace("\n", "").Split(',');
string r = "";
for (int i = 0; i < s.Length; i++)
{
r = r + s[i] + ",";
if ((i + 1) % 3 == 0)
r = r + "+";
}
if (r.Substring(r.Length - 1, 1) == ",")
r = r.Substring(0, r.Length - 1);
if (r.Substring(r.Length - 1, 1) == "+")
r = r.Substring(0, r.Length - 1);
string[] finalArrayString = r.Trim().Split('+');
//just for show the result
textBox1.Text = "";
for (int i = 0; i < finalArrayString.Length; i++)
textBox1.Text = textBox1.Text + finalArrayString[i] + "\r\n";
}
hope it helps you

Split and append a string?

Right now I take in a string like this "112233 112233 112233 112233", and I split it into an array like this:
string text = ProcessString("112233 112233");
string[] dates = text.Split(' ');
And that works great, but I want to use string builder to build my string so they would end up like 11-22-33 11-22-33 etc.
So I did try this:
static string ProcessString(string input)
{
StringBuilder buffer = new StringBuilder(input.Length * 3 / 2);
for (int i = 0; i < input.Length; i++)
{
if ((i > 0) & (i % 2 == 0))
buffer.Append("-");
buffer.Append(input[i]);
}
return buffer.ToString();
}
It works, but it does not match the expected output of:
11-22-33
11-22-33
My current output is:
11-22-33-
1-12-23-3
-11-22-33
What can I do to fix this?

You can process a single string simply by iterating and collecting size-2 substrings of the string, and then joining them by the - character:
string s = "112233";
List<string> parts = new List<string>(s.Length / 2);
for (int i = 0; i < s.Length; i += 2)
parts.Add(s.Substring(i, 2));
Console.WriteLine(string.Join("-", parts)); // 11-22-33
So, for your full problem, you could do this:
static string ProcessString(string input)
{
var segments = input.Split(' ').Select(s =>
{
List<string> parts = new List<string>(s.Length / 2);
for (int i = 0; i < s.Length; i += 2)
parts.Add(s.Substring(i, 2));
return string.Join("-", parts);
});
return string.Join(" ", segments);
}

How about regex:
string s = "112233";
string pattern = #"\d{2}\B";
string result = Regex.Replace(s, pattern, m => m.Value + "-");

Can i offer you another Regex + LINQ approach?
var newDates = dates.Select(d => Regex.Replace(d, ".{2}", "$0-").Trim('-'));
string result = string.Join(" ", newDates);
But i like this extension more because it's readable and re-usable:
public static IEnumerable<String> SplitInParts(this String s, Int32 partLength)
{
if (s == null)
throw new ArgumentNullException("s");
if (partLength <= 0)
throw new ArgumentException("Part length has to be positive.", "partLength");
for (var i = 0; i < s.Length; i += partLength)
yield return s.Substring(i, Math.Min(partLength, s.Length - i));
}
Then the code is even easier:
var newDates = dates.Select(d => string.Join("-", d.SplitInParts(2)));
string result = string.Join(" ", newDates);

I have this approach :
string input = "112233 445566 778899 101010";
string[] dates = input.Split(' ');
foreach (string date in dates){
Console.WriteLine(date);
string result = date.Substring(0, 2) + '-' + date.Substring(2, 2) + "-" + date.Substring(4, 2);
Console.WriteLine(result);
}

You can use Array.ConvertAll:
string str = "112233 112233 112233 112233";
string[] dates = str.Split();
dates = Array.ConvertAll(dates, s => s.Insert(4, "-").Insert(2, "-"));
foreach (var s in dates)
Console.WriteLine(s);

Enter character every 4(th) character in string

I have a string which is gonna be used as a serial its now in format:
XXX1XXX2XXX3XXX4
I would like it formatted as:
XXX1-XXX2-XXX3-XXX4
How can I do this?

Have you tried string.insert?.
MSDN: String.Insert Method
I am sure you can create some logic with it.

So many ways to do this. :)
Here's yet another:
string s = "XXX1XXX2XXX3XXX4";
StringBuilder sb = new StringBuilder();
for (int i = 0; i < s.Length; ++i)
{
sb.Append(s[i]);
if ((i < s.Length-1) && ((i+1) % 4) == 0)
{
sb.Append('-');
}
}
s = sb.ToString();
Console.WriteLine(s);

StringBuilder init = new StringBuilder("XXX1XXX2XXX3XXX4");
string insertVal = "-";
for(int i=4, i<init.length;i=i+5)
{
init.insert(i, inserVal, 1);
}

string str="0123567236359783590203582835";
str.ToCharArray()
.Aggregate("",
(result, c) => result += ((!string.IsNullOrEmpty(result) && (result.Length+1) % 5 == 0)
? "-" : "")
+ c.ToString()
);
// --> 0123-5672-3635-9783-5902-0358-2835

try Using Linq as follow...
var s = "XXX1XXX2XXX3XXX4xx5x";
var list = Enumerable
.Range(0, s.Length/4)
.Select(i => s.Substring(i*4, 4))
.ToList();
var res = string.Join("-", list);
Console.WriteLine("{0}",res);

interview question - how to loop through an array with a different starting point?

Let's say you have the string "This is a test"
I pass it to method zee, like ("This is a test", 1)
and want "test This is a";
I pass it to method zee, like ("This is a test", 2)
and want "a test This is";
the number can exceed the total words in variable. If it does it should loop around.
I started with....
public static string zee(string origString, int i)
{
StringBuilder sb = new StringBuilder();
ArrayList list = new ArrayList();
list.AddRange(origString.Split(' '));
// not sure here -
for (int c = i; c < (list.Count + i); c++)
{
sb.AppendFormat("{0} ", list[c]);
}
return sb.ToString();
}

for(int j=0; j < list.length; j++){
int idx = (j + i) % list.length;
sb.AppendFormat("{0} " , list[idx]);
}
Mostly like Brent Arias's solution, but I think a for loop is more readable, less likely to go infinite.
public static string zee(string origString, int i)
{
StringBuilder sb = new StringBuilder();
List<string> list = new List<string>();
list.AddRange(origString.Split(' '));
for (int j = 0; j < list.Count; j++)
{
int idx = (j + i) % list.Count;
sb.AppendFormat("{0} ", list[idx]);
}
return sb.ToString();
}

This is how I'd solve it.
private static string f(string s, int start)
{
var arr=s.Split(' ');
start %= arr.Length;
var res=arr.Skip(arr.Length - start).ToList();
res.AddRange(arr.Take(arr.Length - start));
return string.Join(" ", res);
}
I tried writing a one liner with linq but I don't see how to combine 2 lists. Union and Join aren't what I need.

This is how I'd solve it using strings.
public static string zee(string origString, int i)
{
string[] splitStr = origString.Split(' ');
string newStr = "";
// Not sure what you meant by wrap around but this should
// do the trick.
i %= splitStr.Length;
for (int j = (splitStr.Length - i); j < splitStr.Length; j++)
newStr += splitStr[j] + " "; // Add spaces taken by split :(
for (int j = 0; j < (splitStr.Length - i); j++)
newStr += splitStr[j] + " ";
return
newStr;
}

Here's an abomination trying to cram as much into one line as possible:
static string zee(string sentence, int wordCount)
{
var words = sentence.Split(' ');
return string.Join(" ", new[] { words.Skip(words.Count() - wordCount), words.Take(words.Count() - wordCount) }.SelectMany(w => w).ToArray());
}

I havn't tried it, but I think this would do it:
i %= list.Length;
int index = i;
do {
index %= list.Length;
sb.AppendFormat("{0} ", list[index]);
while (++index != i);

static string rearrange(string phase,int index)
{
string[] words = phase.Split(' ');
string[] newwords = new string[words.Length];
int pointer = index;
for (int i = 0; i < words.Length;i++ )
{
if(pointer>=words.Length)
{
pointer = 0;
}
newwords[i] = words[pointer];
pointer++;
}
return string.Join(" ", newwords);
}

Sounds like a homework question to me, but here is an efficient use of the .Net framework:
private static string [] SplitWords(string s, int startWord)
{
string[] words = s.Split(' ');
List<string> output = new List<string>();
output.AddRange(words.Skip(startWord).ToArray());
output.AddRange(words.Take(startWord).ToArray());
return output.ToArray();
}
There is absolutely no error checking in this function so you will have to modify it for production code but you get the idea.

public string SetStart(int startAt)
{
const string sentence = "this is a test so it is";
var words = sentence.Split(' ');
var x = (startAt > words.Count()) ? startAt%words.Count() : startAt;
return string.Join(" ", words.Skip(x).Concat(words.Take(x)));
}