LeetCode Substring with Concatenation of All Words

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You are given a string, S, and a list of words, L, that are all of the same length. Find all starting indices of substring(s) in S that is a concatenation of each word in L exactly once and without any intervening characters.

For example, given:
S: "barfoothefoobarman"
L: ["foo", "bar"]

You should return the indices: [0,9].
(order does not matter).

思路：是一道维护一个动态窗口的题目，维护一个[start, end)的窗口来包含L中的串，每次移动的单位都是len(L的串都是同样大小的)

class Solution {
public:
    vector<int> findSubstring(string S, vector<string> &L) {
        map<string, int> wordTimes;
        for (int i = 0; i < L.size(); i++) {
            if (wordTimes.count(L[i]) == 0) 
                wordTimes[L[i]] = 1;
            else wordTimes[L[i]]++;
        }   

        int len = L[0].size();
        vector<int> res;
        for (int i = 0; i < len; i++) {
            map<string, int> curTimes;
            int start = i, cnt = 0;
            for (int end = i; end <= (int)S.size()-len; end += len) {
                string word = S.substr(end, len);
                if (wordTimes.find(word) != wordTimes.end()) {
                    if (curTimes.find(word) == curTimes.end())
                        curTimes[word] = 1;
                    else curTimes[word]++;

                    if (curTimes[word] <= wordTimes[word])
                        cnt++;
                    else {
                        for (int k = start; ; k += len) {
                            string tmp = S.substr(k, len);
                            curTimes[tmp]--;
                            if (tmp == word) {
                                start = k + len;
                                break;
                            }
                            cnt--;
                        }
                    }

                    if (cnt == L.size())
                        res.push_back(start);
                } else {
                    start = end + len;
                    curTimes.clear();
                    cnt = 0;
                } 
            }
        }

        return res;
    }
};

LeetCode Substring with Concatenation of All Words

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原文地址：http://blog.csdn.net/u011345136/article/details/43918199