[*leetcode 30] Substring with Concatenation of All Words

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).

[Solution]

 1 vector<int> findSubstring(string S, vector<string> &L) 
 2     {
 3         map<string, int> wcount;
 4         vector<int> result;
 5         int i = 0, j = 0;
 6         if (L.size() == 0)
 7             return result;
 8             
 9         int len = L[0].size(), lsize = L.size();
10         for (i = 0; i < L.size(); i++)
11             wcount[L[i]]++;
12             
13         for (i = 0; i <= (int)(S.size() - len * lsize); i++)
14         {
15             map<string, int> table;
16             for (j = 0; j < lsize; j++)
17             {
18                 string word = S.substr(i + j * len, len);
19                 if (wcount.find(word) == wcount.end())
20                     break;
21                 table[word]++;
22                 if (table[word] > wcount[word])
23                     break;
24             }
25             if (j == lsize)
26                 result.push_back(i);
27         }
28         
29         return result;
30     }