Count of sub-strings of length n possible from the given string

Given a string str and an integer N, the task is to find the number of possible sub-strings of length N.

Examples:

Input: str = “geeksforgeeks”, n = 5
Output: 9
All possible sub-strings of length 5 are “geeks”, “eeksf”, “eksfo”,
“ksfor”, “sforg”, “forge”, “orgee”, “rgeek” and “geeks”.

Input: str = “jgec”, N = 2
Output: 3

Approach: The count of sub-strings of length n will always be len – n + 1 where len is the length of the given string. For example, if str = “geeksforgeeks” and n = 5 then the count of sub-strings having length 5 will be “geeks”, “eeksf”, “eksfo”, “ksfor”, “sforg”, “forge”, “orgee”, “rgeek” and “geeks” which is len – n + 1 = 13 – 5 + 1 = 9.

Below is the implementation of the above approach:

C++

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// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
  
// Function to return the count of
// possible sub-strings of length n
int countSubStr(string str, int n)
{
    int len = str.length();
    return (len - n + 1);
}
  
// Driver code
int main()
{
    string str = "geeksforgeeks";
    int n = 5;
  
    cout << countSubStr(str, n);
  
    return 0;
}

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Java

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// Java implementation of the approach
import java.util.*; 
  
class GFG
{
  
// Function to return the count of
// possible sub-strings of length n
static int countSubStr(String str, int n)
{
    int len = str.length();
    return (len - n + 1);
}
  
// Driver code
public static void main(String args[]) 
{
    String str = "geeksforgeeks";
    int n = 5;
  
    System.out.print(countSubStr(str, n));
}
}
  
// This code is contributed by mohit kumar 29

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Python3

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# Python3 implementation of the approach 
  
# Function to return the count of 
# possible sub-strings of length n 
def countSubStr(string, n) : 
  
    length = len(string); 
    return (length - n + 1); 
  
# Driver code 
if __name__ == "__main__"
  
    string = "geeksforgeeks"
    n = 5
  
    print(countSubStr(string, n));
      
# This code is contributed by Ryuga

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C#

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// C# implementation of the approach
using System;
  
class GFG
{
  
// Function to return the count of
// possible sub-strings of length n
static int countSubStr(string str, int n)
{
    int len = str.Length;
    return (len - n + 1);
}
  
// Driver code
public static void Main() 
{
    string str = "geeksforgeeks";
    int n = 5;
  
    Console.WriteLine(countSubStr(str, n));
}
}
  
// This code is contributed by Code_Mech.

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PHP

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<?php
// PHP implementation of the approach
  
// Function to return the count of
// possible sub-strings of length n
function countSubStr($str, $n)
{
    $len = strlen($str);
    return ($len - $n + 1);
}
  
// Driver code
$str = "geeksforgeeks";
$n = 5;
  
echo(countSubStr($str, $n));
  
// This code is contributed by Code_Mech.
?>

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Output:

9


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