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Check if a String is Subsequence of Other

Tags : string, geeksforgeeks, cpp, medium

Problem Statement - link #

Given two strings A and B, find if A is a subsequence of B. A subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements.

Your Task: You dont need to read input or print anything. Complete the function isSubSequence() which takes A and B as input parameters and returns a boolean value denoting if A is a subsequence of B or not.

Expected Time Complexity: O(N) where N is length of string B. Expected Auxiliary Space: O(1)

Examples #

Example 1:

Input:
A = AXY 
B = YADXCP
Output: False
Explanation: A is not a subsequence of B
as 'Y' appears before 'A'.

Example 2:

Input:
A = gksrek
B = geeksforgeeks
Output: True
Explanation: A is a subsequence of B.

Constraints #

Solutions #

class Solution{
    public:
    //Function to check if a string is subsequence of other string.
    bool isSubSequence(string A, string B)
    {
        //code here
        int n=A.size(),m=B.size();
        int i=0,j=0;
        while(i<n&&j<m){
            if(A[i]==B[j]){i++;j++;}
            else j++; 
            if(i==n) return true;
        }

        return false;
        
    }
};