leetcode/lcci/17.13.Re-Space/Solution.cpp

class Solution {
public:
    int respace(vector<string>& dictionary, string sentence) {
        unordered_set<string> s(dictionary.begin(), dictionary.end());
        int n = sentence.size();
        vector<int> dp(n + 1);
        for (int i = 1; i <= n; ++i) {
            dp[i] = dp[i - 1] + 1;
            for (int j = 0; j < i; ++j) {
                if (s.count(sentence.substr(j, i - j))) {
                    dp[i] = min(dp[i], dp[j]);
                }
            }
        }
        return dp[n];
    }
};