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Largest substring with same Characters

  • Difficulty Level : Medium
  • Last Updated : 28 May, 2021
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Given a string s of size N. The task is to find the largest substring which consists of same characters
Examples: 
 

Input : s = “abcdddddeff” 
Output :
Substring is “ddddd”
Input : s = aabceebeee 
Output :
 

 

Approach : 
Traverse through the string from left to right. Take two variables ans and temp. If the current element is the same as the previous element then increment temp. If the current element is not equals to the previous element then make temp as 1 and update ans.
Below is the implementation of the above approach : 
 

C++




// CPP program to find largest sub
// string with same characters
#include <bits/stdc++.h>
using namespace std;
 
// Function to find largest sub
// string with same characters
int Substring(string s)
{
 
    int ans = 1, temp = 1;
 
    // Traverse the string
    for (int i = 1; i < s.size(); i++) {
        // If character is same as
        // previous increment temp value
        if (s[i] == s[i - 1]) {
            ++temp;
        }
        else {
            ans = max(ans, temp);
            temp = 1;
        }
    }
    ans = max(ans, temp);
 
    // Return the required answer
    return ans;
}
 
// Driver code
int main()
{
    string s = "abcdddddeff";
 
    // Function call
    cout << Substring(s);
 
    return 0;
}

Java




// Java program to find largest sub
// string with same characters
import java.util.*;
 
class GFG
{
 
// Function to find largest sub
// string with same characters
static int Substring(String s)
{
    int ans = 1, temp = 1;
 
    // Traverse the string
    for (int i = 1; i < s.length(); i++)
    {
        // If character is same as
        // previous increment temp value
        if (s.charAt(i) == s.charAt(i - 1))
        {
            ++temp;
        }
        else
        {
            ans = Math.max(ans, temp);
            temp = 1;
        }
    }
    ans = Math.max(ans, temp);
 
    // Return the required answer
    return ans;
}
 
// Driver code
public static void main(String[] args)
{
    String s = "abcdddddeff";
 
    // Function call
    System.out.println(Substring(s));
}
}
 
// This code is contributed by 29AjayKumar

Python3




# Python3 program to find largest sub
# with same characters
 
# Function to find largest sub
# with same characters
def Substring(s):
 
    ans, temp = 1, 1
 
    # Traverse the string
    for i in range(1, len(s)):
         
        # If character is same as
        # previous increment temp value
        if (s[i] == s[i - 1]):
            temp += 1
        else:
            ans = max(ans, temp)
            temp = 1
 
    ans = max(ans, temp)
 
    # Return the required answer
    return ans
 
# Driver code
s = "abcdddddeff"
 
# Function call
print(Substring(s))
 
# This code is contributed by Mohit Kumar

C#




// C# program to find largest sub
// string with same characters
using System;
class GFG
{
 
// Function to find largest sub
// string with same characters
static int Substring(String s)
{
    int ans = 1, temp = 1;
 
    // Traverse the string
    for (int i = 1; i < s.Length; i++)
    {
        // If character is same as
        // previous increment temp value
        if (s[i] == s[i - 1])
        {
            ++temp;
        }
        else
        {
            ans = Math.Max(ans, temp);
            temp = 1;
        }
    }
    ans = Math.Max(ans, temp);
 
    // Return the required answer
    return ans;
}
 
// Driver code
public static void Main(String[] args)
{
    String s = "abcdddddeff";
 
    // Function call
    Console.WriteLine(Substring(s));
}
}
 
// This code is contributed by Rajput-Ji

PHP




<?php
// PHP program to find largest sub
// string with same characters
 
// Function to find largest sub
// string with same characters
function Substring($s)
{
    $ans = 1;
    $temp = 1;
     
    // Traverse the string
    for ($i = 1; $i < strlen($s); $i++)
    {
         
        // If character is same as
        // previous increment temp value
        if ($s[$i] == $s[$i - 1])
        {
            ++$temp;
        }
        else
        {
            $ans = max($ans, $temp);
            $temp = 1;
        }
    }
     
    $ans = max($ans, $temp);
 
    // Return the required answer
    return $ans;
}
 
// Driver code
$s = "abcdddddeff";
 
// Function call
echo Substring($s);
     
// This code is contributed by Naman_Garg
?>

Javascript




<script>
 
// Javascript program to find largest sub
// string with same characters
 
// Function to find largest sub
// string with same characters
function Substring(s)
{
 
    var ans = 1, temp = 1;
 
    // Traverse the string
    for (var i = 1; i < s.length; i++) {
        // If character is same as
        // previous increment temp value
        if (s[i] == s[i - 1]) {
            ++temp;
        }
        else {
            ans = Math.max(ans, temp);
            temp = 1;
        }
    }
    ans = Math.max(ans, temp);
 
    // Return the required answer
    return ans;
}
 
// Driver code
var s = "abcdddddeff";
// Function call
document.write( Substring(s));
 
</script>

Output: 
 



5

Time Complexity: O(N)
 

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