POJ 3461 KMP

Posted 2020-09-15 Flowersea

链接：

http://poj.org/problem?id=3461

代码：

31 char a[MAXN], b[MAXN];
32 int sum;
33 
34 int* buildNext(char *P) {
35     size_t m = strlen(P), j = 0;
36     int *N = new int[m];
37     int t = N[0] = -1;
38     while (j < m - 1) {
39         if (0 > t || P[j] == P[t]) j++, t++, N[j] = t;
40         else t = N[t];
41     }
42     return N;
43 }
44 
45 void match(char *P, char *T) {
46     int *next = buildNext(P);
47     int n = strlen(T), i = 0;
48     int m = strlen(P), j = 0;
49     while (i < n) {    
50         if (0 > j || T[i] == P[j]) {
51             if (j == m - 1) {
52                 j = next[j], sum++;
53                 continue;
54             }
55             i++, j++;
56         }
57         else j = next[j];
58     }
59     delete[] next;
60 }
61 
62 int main() {
63     int T;
64     cin >> T;
65     while (T--) {
66         sum = 0;
67         scanf("%s%s", a, b);
68         match(a, b);
69         cout << sum << endl;
70     }
71     return 0;
72 }