139. 单词拆分——动态规划

class Solution {
public:
    bool wordBreak(string s, vector<string>& wordDict) {
        auto words = unordered_set<string>();
        for(auto word : wordDict){
            words.insert(word);
        }
        auto dp = vector<bool>(s.size() + 1);   //整体往后一位，所以要多加1个长度
        dp[0] = true;
        for(int i = 1; i <= s.size(); ++i){
            for(int j = 0; j < i; ++j){
                if(dp[j]    //前面都已经配对上了
                 && words.count(s.substr(j, i - j))){   //目前检索的这段也配对上了
                    dp[i] = true;
                    break;
                }
            }
        }
        return dp[s.size()];
    }
};

Accepted
45/45 cases passed (12 ms)
Your runtime beats 63.27 % of cpp submissions
Your memory usage beats 48.98 % of cpp submissions (12.8 MB)