【LeetCode算法練習（C++）】Substring with Concatenation of All Words

題目：
You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once and without any intervening characters.
For example, given:
s: “barfoothefoobarman”
words: [“foo”, “bar”]
You should return the indices: [0,9].
(order does not matter).

鏈接：Substring with Concatenation of All Words
解法：枚舉子串，切分後用map判斷。時間O(n*m)

class Solution {
public:
    vector<int> findSubstring(string s, vector<string>& words) {
        map<string, int> mwords;
        map<string, int> curWords;
        vector<int> ret;
        int slen = s.length();
        if (!slen || words.empty()) return ret;
        int llen = words.size(), wlen = words[0].length();
        for (vector<string>::iterator i = words.begin(); i != words.end(); i++) mwords[*i]++;
        for (int i = 0; i + llen * wlen <= slen; i++) {
            curWords.clear();
            int j = 0;
            for (j = 0; j < llen; j++) {
                string tmp = s.substr(i + j * wlen, wlen);
                if (mwords.find(tmp) == mwords.end())
                    break;
                ++curWords[tmp];
                if (curWords[tmp] > mwords[tmp])
                    break;
            }
            if (j == llen) ret.push_back(i);
        }
        return ret;
    };
};

Runtime: 152 ms