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leetcode - Substring with Concatenation of All Words

2013-12-16 21:12  张汉生  阅读(191)  评论(0)    收藏  举报

 

 1 class Solution {
 2 public:
 3     typedef unordered_map<string,int> HashMap;
 4     bool canMatch(const char* head, const char * end, HashMap & flags, int l){
 5         if (head == end+1)
 6             return true;
 7         string s="";
 8         for (int i=0; i<l; i++)
 9             s+= *(head+i);
10         HashMap::iterator hi = flags.find(s);
11         if (hi==flags.end() || hi->second<=0)
12             return false;
13         flags[s]--;
14         bool rlt = canMatch(head+l,end,flags,l);
15         flags[s]++;
16         return rlt;
17     }
18     vector<int> findSubstring(string S, vector<string> &L) {
19         // IMPORTANT: Please reset any member data you declared, as
20         // the same Solution instance will be reused for each test case.
21         vector<int> rlt;
22         int n = L.size();
23         if (n<=0)
24             return rlt;
25         int l = L[0].length();
26         if (l<=0)
27             return rlt;
28         HashMap flags;
29         for (int i=0; i<n; i++){
30             if (flags.find(L[i]) == flags.end())
31                 flags[L[i]]=1;
32             else flags[L[i]]++;
33         }
34         const char * head = S.c_str();
35         for (int i=0; i+l*n<=S.length(); i++){
36             if (canMatch(head+i, head+i+l*n-1, flags, l))
37                 rlt.push_back(i);
38         }
39         return rlt;
40     }
41 };