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KMP的具体算法讲解可以参考此博文
http://blog.csdn.net/v_july_v/article/details/7041827
KMP算法的应用
http://poj.org/problem?id=2406
首先求得next数组
若基础字符串为t，输入字符串为s，若s=t^n；那么下面的等式必然满足
next(strlen(s)) = strlen(s)-strlen(t);
同时n = strlen(s)/strlen(t)，此时必须满足strlen(s) % strlen(t) == 0
否则 n=1
1 #include <iostream> 2 #include <cstring> 3 #include <cstdio> 4 using namespace std; 5 6 const int N = 1000001; 7 char s[N]; 8 int _next[N]; 9 10 void getNext() 11 { 12 int k,j; 13 k = -1; 14 j = 0; 15 _next[0] = -1; 16 int len = strlen(s); 17 18 while(j < len) 19 { 20 if(s[k] == s[j] || k == -1) 21 { 22 k++; 23 j++; 24 _next[j] = k; 25 } 26 else 27 { 28 k = _next[k]; 29 } 30 } 31 } 32 33 int main() 34 { 35 while(scanf("%s", s)) 36 { 37 if(strcmp(s, ".") == 0) 38 { 39 break; 40 } 41 memset(_next, 0, sizeof(_next)); 42 int len = strlen(s); 43 getNext(); 44 45 int t = len - _next[len]; 46 int res; 47 48 if(len % t == 0) 49 { 50 res = len / t; 51 } 52 else 53 { 54 res = 1; 55 } 56 cout<<res<<endl; 57 } 58 return 0; 59 }
http://poj.org/problem?id=1961
与上一题类似
1 #include <cstdio> 2 #include <iostream> 3 #include <cstring> 4 using namespace std; 5 6 const int N = 1000001; 7 int _next[N]; 8 char s[N]; 9 int n; 10 11 void getNext() 12 { 13 int k,j; 14 k = -1; 15 j = 0; 16 _next[0] = -1; 17 18 while(j < n) 19 { 20 if(s[k] == s[j] || k == -1) 21 { 22 k++; 23 j++; 24 _next[j] = k; 25 } 26 else 27 { 28 k = _next[k]; 29 } 30 } 31 } 32 33 int main() 34 { 35 int nCase = 0; 36 while(scanf("%d", &n) && n) 37 { 38 scanf("%s", s); 39 40 nCase++; 41 memset(_next, 0, sizeof(_next)); 42 getNext(); 43 44 printf("Test case #%d\n", nCase); 45 for(int i = 2; i <= n; i++) 46 { 47 if(_next[i] > 0) 48 { 49 int ans = i - _next[i]; 50 if(i % ans == 0) 51 { 52 printf("%d %d\n", i, i/ans); 53 } 54 } 55 } 56 printf("\n"); 57 } 58 59 return 0; 60 }
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原文地址：http://www.cnblogs.com/ygw0616/p/4508116.html
