Subsequence Strings - Amazon Top Interview Questions


Problem Statement :


Given two lowercase alphabet strings s1 and s2, determine if s1 is a subsequence of s2.

Constraints

n ≤ 100,000 where n is the length of s1
m ≤ 100,000 where m is the length of s2

Example 1

Input

s1 = "ppl"
s2 = "apple"

Output

True

Example 2

Input

s1 = "ale"
s2 = "apple"

Output

True

Example 3

Input

s1 = "elppa"
s2 = "apple"

Output

False


Solution :



title-img 




                        Solution in C++ :

bool solve(string s1, string s2) {
    int j = 0;
    for (int i = 0; i < s2.length() && j < s1.length(); i++) {
        if (s1[j] == s2[i]) j++;
    }
    return (j == (int)s1.length());
}
                    




                        Solution in Python : 
                            
class Solution:
    def solve(self, s1, s2):
        n = len(s1)
        m = len(s2)
        s1_ptr = 0
        s2_ptr = 0
        while s1_ptr < n and s2_ptr < m:
            if s1[s1_ptr] == s2[s2_ptr]:
                s1_ptr += 1
            s2_ptr += 1

        return s1_ptr == n


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