[hihoCoder] KMP算法

Each time we find a match, increase the global counter by 1.

For KMP, algorithm, you may refer to the following links which have nice explanations.

1. KMP on jBoxer's blog;
2. KMP on geeksforgeeks, with a well-commented C code.

 #include <iostream>
 #include <string>
 #include <vector>

 using namespace std;

 vector<int> kmpProcess(string t) {
     int n = t.length();
     vector<int> lps(n, );
     for (int i = , len = ; i < n; ) {
         if (t[i] == t[len])
             lps[i++] = ++len;
         else if (len) len = lps[len - ];
         else lps[i++] = ;
     }
     return lps;
 }

 int kmp(string s, string t) {
     int m = s.length(), n = t.length(), cnts = ;
     vector<int> lps = kmpProcess(t);
     for (int i = , j = ; i < m; ) {
         if (s[i] == t[j]) {
             i++;
             j++;
         }
         if (j == n) cnts++;
         if (i < m && s[i] != t[j]) {
             if (j) j = lps[j - ];
             else i++;
         }
     }
     return cnts;
 }

 int main(void) {
     int cases;
     scanf("%d", &cases);
     for (int i = ; i < cases; i++) {
         string s, t;
         cin >> t;
         cin >> s;
         printf("%d\n", kmp(s, t));
     }
     return ;
 }