Check if a string can be split into two substrings such that one substring is a substring of the other

Given a string S of length N, the task is to check if a string can be split into two substrings, say A and B such that B is a substring of A. If not possible, print No. Otherwise, print Yes.

Examples :

Input: S = “abcdab”
Output: Yes
Explanation: Considering the two splits to be A=”abcd” and B=”ab”, B is a substring of A.

Input: S = “abcd”
Output: No

Naive Approach: The simplest approach to solve the problem is to split the string S at every possible index, and check if the right substring is a substring of the left substring. If any split satisfies the condition, print “Yes“. Otherwise, print “No“. 

Time Complexity: O(N²)
Auxiliary Space: O(1)

Efficient Approach: To optimize the above approach, the idea is to check if the last character of the string S is present in the remaining string or not. Follow the steps below to solve the problem:

• Store the last character of S in c.
• Check if c is present in the substring S[0, N-2].
• If found to be true, print “YES”. otherwise print “NO”.

Below is the implementation of the above approach:

C++

// C++ program to implement
// the above approach
#include <bits/stdc++.h>
using namespace std;

// Function to check if a string can be
// divided into two substrings such that
// one substring is substring of the other
void splitString(string S, int N)
{
    // Store the last character of S
    char c = S[N - 1];

    int f = 0;

    // Traverse the characters at indices [0, N-2]
    for (int i = 0; i < N - 1; i++) {

        // Check if the current character is
        // equal to the last character
        if (S[i] == c) {

            // If true, set f = 1
            f = 1;

            // Break out of the loop
            break;
        }
    }

    if (f)
        cout << "Yes";
    else
        cout << "No";
}

// Driver Code
int main()
{
    // Given string, S
    string S = "abcdab";

    // Store the size of S
    int N = S.size();

    // Function Call
    splitString(S, N);

    return 0;
}

Java

// Java program to implement
// the above approach
import java.util.*;
class GFG{

// Function to check if a String can be
// divided into two subStrings such that
// one subString is subString of the other
static void splitString(String S, int N)
{

    // Store the last character of S
    char c = S.charAt(N - 1);
    int f = 0;

    // Traverse the characters at indices [0, N-2]
    for (int i = 0; i < N - 1; i++)
    {

        // Check if the current character is
        // equal to the last character
        if (S.charAt(i) == c)
        {

            // If true, set f = 1
            f = 1;

            // Break out of the loop
            break;
        }
    }

    if (f > 0)
        System.out.print("Yes");
    else
        System.out.print("No");
}

// Driver Code
public static void main(String[] args)
{

    // Given String, S
    String S = "abcdab";

    // Store the size of S
    int N = S.length();

    // Function Call
    splitString(S, N);
}
}

// This code is contributed by 29AjayKumar

Python3

# Python3 program to implement
# the above approach

# Function to check if a can be
# divided into two substrings such that
# one subis subof the other
def splitString(S, N):

    # Store the last character of S
    c = S[N - 1]

    f = 0

    # Traverse the characters at indices [0, N-2]
    for i in range(N - 1):

        # Check if the current character is
        # equal to the last character
        if (S[i] == c):

            # If true, set f = 1
            f = 1

            # Break out of the loop
            break

    if (f):
        print("Yes")
    else:
        print("No")

# Driver Code
if __name__ == '__main__':

    # Given string, S
    S = "abcdab"

    # Store the size of S
    N = len(S)

    # Function Call
    splitString(S, N)

# This code is contributed by mohit kumar 29

C#

// C# program to implement
// the above approach
using System;
class GFG{

// Function to check if a string can be
// divided into two substrings such that
// one substring is substring of the other
static void splitString(string S, int N)
{
    // Store the last character of S
    char c = S[N - 1];
    int f = 0;

    // Traverse the characters at indices [0, N-2]
    for (int i = 0; i < N - 1; i++)
    {

        // Check if the current character is
        // equal to the last character
        if (S[i] == c)
        {

            // If true, set f = 1
            f = 1;

            // Break out of the loop
            break;
        }
    }

    if (f != 0)
        Console.Write("Yes");
    else
        Console.Write("No");
}

// Driver code
public static void Main()
{
    // Given string, S
    string S = "abcdab";

    // Store the size of S
    int N = S.Length;

    // Function Call
    splitString(S, N);
}
}

// This code is contributed by susmitakundugoaldanga

Javascript

<script>

// JavaScript program to implement
// the above approach
// Function to check if a String can be
// divided into two subStrings such that
// one subString is subString of the other
function splitString(S , N)
{

    // Store the last character of S
    var c = S.charAt(N - 1);
    var f = 0;

    // Traverse the characters at indices [0, N-2]
    for (var i = 0; i < N - 1; i++)
    {

        // Check if the current character is
        // equal to the last character
        if (S.charAt(i) == c)
        {

            // If true, set f = 1
            f = 1;

            // Break out of the loop
            break;
        }
    }

    if (f > 0)
        document.write("Yes");
    else
        document.write("No");
}

// Driver Code

//Given String, S
var S = "abcdab";

// Store the size of S
var N = S.length;

// Function Call
splitString(S, N);

// This code contributed by shikhasingrajput

</script>

Output:

Yes

Time Complexity: O(N)
Auxiliary Space: O(1)