KMP算法模板

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<algorithm>
 5 #include<cstring>
 6 #include<vector>
 7 using namespace std;
 8 int N, fail[2000000], ANS[2000000];
 9 char pat[2000000], text[2000000];
10 inline void KMP() {
11     int n = strlen(pat);
12     for (int i = 0; i <= n + 1; i++) fail[i] = 0;
13     for (int i = 1; i <= n - 1; i++) {
14         int j = i;
15         while (j>0) {
16             j = fail[j];
17             if (pat[j] == pat[i]) {
18                 fail[i + 1] = j + 1;
19                 break;
20             }
21         }
22     }
23     ANS[0] = 0;
24     int m = strlen(text);
25     for (int i = 0, j = 0; i <= m - 1; i++) {
26         if (j <= n - 1 && text[i] == pat[j]) j++;
27         else {
28             while (j > 0) {
29                 j = fail[j];
30                 if (text[i] == pat[j]) {
31                     j++; break;
32                 }
33             }
34         }
35         if (j == n) ANS[++ANS[0]] = i - n + 1;
36     }
37 }
38 int main() {
39     scanf("%d", &N);
40     while (N--) {
41         cin >> pat >> text;
42         KMP();
43         printf("%d\n", ANS[0]);
44     }
45     return 0;
46 }

 

转载于:https://www.cnblogs.com/CXCXCXC/p/4681625.html