2486-Append-Characters-to-String-to-Make-Subsequence.ts

function appendCharacters(s: string, t: string): number {
    let sPointer = 0
    let tPointer = 0

    while (sPointer < s.length && tPointer < t.length) {
        if (s[sPointer] === t[tPointer]) {
            tPointer++
        }
        sPointer++
    }

    return t.length - tPointer

};