isSubsequence.js

// LeetCode #392. Is Subsequence
/* Instructions
Given two strings s and t, return true if s is a subsequence of t, or false otherwise.

A subsequence of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e., "ace" is a subsequence of "abcde" while "aec" is not).

 

Example 1:

Input: s = "abc", t = "ahbgdc"
Output: true

Example 2:

Input: s = "axc", t = "ahbgdc"
Output: false

 

Constraints:

    0 <= s.length <= 100
    0 <= t.length <= 104
    s and t consist only of lowercase English letters.

 
Follow up: Suppose there are lots of incoming s, say s1, s2, ..., sk where k >= 109, and you want to check one by one to see if t has its subsequence. In this scenario, how would you change your code?
*/

// Solution
function isSubsequence(s, t) {
    // split t into an array of characters
    t = t.split('')

    // loop through the array, and if array is not equal to the current value of s, remove it
    for (let i = 0; i < t.length; i++) {
        if (t[i] !== s[i]) {
            t.splice(i, 1)
            i--
        }
    }
    // join t back into a string
    t = t.join('')

    // if s and t are comparatively equal, then return true otherwise false
    return (s === t)
}