Count of sub-strings that contain character X at least once

Given a string str and a character X. The task is to find the total number of sub-strings that contain the character X at least once.

Examples:

Input: str = “abcd”, X = ‘b’
Output: 6
“ab”, “abc”, “abcd”, “b”, “bc” and “bcd” are the required sub-strings.

Input: str = “geeksforgeeks”, X = ‘e’
Output: 66

Approach: Total number of sub-strings are n * (n + 1) / 2, among them only those sub-strings need to be counted which contain character X. Character X is present in those sub-strings from position of X to the length of the string. For each character before X this sub-string must be counted.

Below is the implementation of the above approach:

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
  
// Function to return the count of
// required sub-strings
int countSubStr(string str, int n, char x)
{
    int res = 0, count = 0;
    for (int i = 0; i < n; i++) {
        if (str[i] == x) {
  
            // Number of sub-strings from position
            // of current x to the end of str
            res += ((count + 1) * (n - i));
  
            // To store the number of characters
            // before x
            count = 0;
        }
        else
            count++;
    }
  
    return res;
}
  
// Driver code
int main()
{
    string str = "abcabc";
    int n = str.length();
    char x = 'c';
  
    cout << countSubStr(str, n, x);
  
    return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java implementation of the approach
class GFG 
{
  
// Function to return the count of
// required sub-strings
static int countSubStr(String str, int n, char x)
{
    int res = 0, count = 0;
    for (int i = 0; i < n; i++)
    {
        if (str.charAt(i) == x)
        {
  
            // Number of sub-strings from position
            // of current x to the end of str
            res += ((count + 1) * (n - i));
  
            // To store the number of characters
            // before x
            count = 0;
        }
        else
            count++;
    }
  
    return res;
}
  
// Driver code
public static void main(String[] args)
{
    String str = "abcabc";
    int n = str.length();
    char x = 'c';
  
    System.out.println(countSubStr(str, n, x));
}
}
  
// This code has been contributed by 29AjayKumar

chevron_right


Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python implementation of the approach 
   
# Function to return the count of 
# required sub-strings 
def countSubStr(str, n, x): 
    res = 0; count = 0
    for i in range(n): 
        if (str[i] == x): 
   
            # Number of sub-strings from position 
            # of current x to the end of str 
            res += ((count + 1) * (n - i)); 
   
            # To store the number of characters 
            # before x 
            count = 0
        else:
            count+=1
   
    return res; 
  
# Driver code 
str = "abcabc"
n = len(str); 
x = 'c'
   
print(countSubStr(str, n, x));
  
# This code contributed by PrinciRaj1992

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// C# implementation of the approach
using System;
  
class GFG 
{
  
// Function to return the count of
// required sub-strings
static int countSubStr(String str, int n, char x)
{
    int res = 0, count = 0;
    for (int i = 0; i < n; i++)
    {
        if (str[i] == x)
        {
  
            // Number of sub-strings from position
            // of current x to the end of str
            res += ((count + 1) * (n - i));
  
            // To store the number of characters
            // before x
            count = 0;
        }
        else
            count++;
    }
  
    return res;
}
  
// Driver code
public static void Main(String[] args)
{
    String str = "abcabc";
    int n = str.Length;
    char x = 'c';
  
    Console.WriteLine(countSubStr(str, n, x));
}
}
  
/* This code contributed by PrinciRaj1992 */

chevron_right


PHP

filter_none

edit
close

play_arrow

link
brightness_4
code

<?php
// PHP implementation of the approach 
  
// Function to return the count of 
// required sub-strings 
function countSubStr($str, $n, $x
    $res = 0; $count = 0; 
    for ($i = 0; $i < $n; $i++)
    
        if ($str[$i] == $x
        
  
            // Number of sub-strings from position 
            // of current x to the end of str 
            $res += (($count + 1) * ($n - $i)); 
  
            // To store the number of characters 
            // before x 
            $count = 0; 
        
        else
            $count++; 
    
  
    return $res
  
// Driver code 
$str = "abcabc"
$n = strlen($str); 
$x = 'c'
  
echo countSubStr($str, $n, $x); 
  
// This code is contributed by Ryuga
?>

chevron_right


Output:

15


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.





Article Tags :
Practice Tags :


Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.