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Minimum number of deletions so that no two consecutive are same
  • Difficulty Level : Basic
  • Last Updated : 28 May, 2018
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Given a string, find minimum number of deletions required so that there will be no two consecutive repeating characters in the string.

Examples:

Input : AAABBB
Output : 4
Explanation : New string should be AB

Input : ABABABAB
Output : 0
Explanation : There are no consecutive repeating characters.

If there are n consecutive same characters delete n-1 out of those n characters.

C++




// CPP code to count minimum deletions required
// so that there are no consecutive characters left
#include <bits/stdc++.h>
using namespace std;
  
int countDeletions(string str)
{
    int ans = 0;
    for (int i = 0; i < str.length() - 1; i++) 
         
        // If two consecutive characters are 
        // the same, delete one of them.
        if (str[i] == str[i + 1]) 
            ans++;
          
   return ans;
}
  
// Driver code
int main()
{
    string str = "AAABBB";
  
    // Function call to print answer
    cout << countDeletions(str);
  
    return 0;
}

Java




// Java code to count minimum deletions required
// so that there are no consecutive characters left
import java.util.*;
  
class GFG
{
  static int countDeletions(String s)
  {
    int ans = 0;
    char[] str = s.toCharArray();
  
    for (int i = 0; i < str.length - 1; i++) 
          
        // If two consecutive characters are 
        // the same, delete one of them.
        if (str[i] == str[i + 1]) 
            ans++;            
        
        return ans;
  }
  
    // Driver code
    public static void main(String[] args)
    {
      String str = "AAABBB";
      // Function call to print answer 
     System.out.println(countDeletions(str));
    }
}
/* This code is contributed by Mr. Somesh Awasthi */

Python




# Python code to count minimum deletions required
# so that there are no consecutive characters left\
  
def countDeletions(string):
    ans = 0
    for i in range(len(string) - 1):
          
        # If two consecutive characters are 
        # the same, delete one of them.
        if (string[i] == string[i + 1]): 
            ans += 1
          
    return ans
   
# Driver code
string = "AAABBB"
  
# Function call to print answer
print countDeletions(string)
  
# This code is contributed by Sachin Bisht

C#




// C# Program to count minimum deletions
// required so that there are no
// consecutive characters left
using System;
  
class GFG
{
      
// Function for counting deletions    
static int countDeletions(String s)
{
    int ans = 0;
    char []str = s.ToCharArray();
  
    for (int i = 0; i < str.Length - 1; i++) 
          
        // If two consecutive characters are 
        // the same, delete one of them.
        if (str[i] == str[i + 1]) 
            ans++;         
      
        return ans;
}
  
    // Driver code
    public static void Main()
    {
        String str = "AAABBB";
      
        // Function call to print answer 
        Console.Write(countDeletions(str));
    }
}
  
// This code is contributed by Nitin Mittal.

PHP




<?php
// PHP code to count minimum 
// deletions required so that
// there are no consecutive 
// characters left
  
function countDeletions($str)
{
    $ans = 0;
    for ($i = 0; $i < strlen($str) - 1; $i++) 
          
        // If two consecutive characters are 
        // the same, delete one of them.
        if ($str[$i] == $str[$i + 1]) 
            $ans++;
          
return $ans;
}
  
    // Driver Code
    $str = "AAABBB";
  
    // Function call to
    // print answer
    echo countDeletions($str);
      
// This code is contributed by nitin mittal
?>


Output:
4

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