Word Break

classic.js

var wordBreak = function(s, wordDict) {
    let dict = new Set(wordDict);
    let isValid = Array(s.length + 1).fill(false);
    isValid[0] = true;
    
    for (let i = 1; i <= s.length; i++) {
        for (let j = 0; j < i; j++) {
            if (isValid[j] && dict.has(s.substring(j, i))) {
                isValid[i] = true;
                break;
            }
        }
    }
    
    return isValid[s.length];
};