字符串匹配：KMP算法

 1 /*Sample Input:
 2   abcegfabcd
 3   abc
 4   
 5   Sample Output:
 6   pos: 0
 7   pos: 6
 8 
 9   输入文本串T和模式串P，输出的是所有的匹配成功的位置 
10 */
11 
12 #include<bits/stdc++.h>
13 using namespace std;
14 int next[10010];
15 
16 void getNext(char arr[]){
17     int len = strlen(arr);
18     next[0] = -1;
19     int k = -1;
20     int j = 0;
21     
22     while(j < len){
23         if(k == -1 || arr[j] == arr[k]){
24             j++;
25             k++;
26             next[j] = k;
27         }
28         else{
29             k = next[k];
30         }
31     }
32 }
33 
34 void KMP(char *P, char *T){
35     int Plen = strlen(P);
36     int Tlen = strlen(T);
37     getNext(T);
38     int j = 0;
39     for(int i = 0; i < Tlen; i++){
40         if(T[i] == P[j]){
41             j++;
42         }
43         else{
44             j = next[j];
45             if(j == -1) j = 0;
46             else i--;
47         }
48         
49         if(j == Plen){
50             cout << "pos: " << i - Plen + 1 << endl;
51             j = 0;
52         }
53     }
54 }
55 int main(){
56     char arr1[20];
57     char arr2[5];
58     scanf("%s", arr1);
59     scanf("%s", arr2);
60     KMP(arr2, arr1);
61 }