💡 Intuition

• We can iterate through the characters of the main string while keeping track of the index in the subsequence.
• Whenever we find a matching character, we move to the next character in the subsequence.
• If we successfully traverse the entire subsequence, it confirms that it is present in the main string.

🚀 Solution

function isSubsequence(s: string, t: string): boolean {
    let indx = 0;

    for ( let i = 0 ; i < t.length; i++ ) {
        if ( indx < s.length && s[indx] == t[i] ) {
            indx = indx+1;
        }
    }

    if (indx == s.length) {
        return true;
    }

    return false;
};

⏳ Time Complexity

• Since we are taking single loop for the array of length n, the time complexity will be O(n)