isSubsequenceの問題の解決

説明する

/*
 문제
	Write a function called isSubsequence
	which takes in two strings and checks
	whether the characters in the first string
	form a subsequence of the characters in the second string.
	In other words, the function should check
	whether the characters in the first string
	appear somewhere in the second string,
	without their order changing.

	Your solution MUST have AT LEAST the following complexities:
		Time Complexity - O(N + M)
		Space Complexity - O(1)
 */
function isSubsequence(a, b) {
    let idxA = 0;
    let idxB = 0;
    while (idxA < a.length && idxB < b.length) {
        if (a[idxA] === b[idxB]) {
            idxA++;
            idxB++;
        } else {
            idxB++;
        }
    }
    if (idxA === a.length) {
        return true;
    } else {
        return false;
    }
}
console.log(isSubsequence('hello', 'hello world')); // true
console.log(isSubsequence('sing', 'sting')); // true
console.log(isSubsequence('abc', 'abracadabra')); // true
console.log(isSubsequence('abc', 'acb')); // false (order matters)

解説