Ultraviolet A 10298-power strings

Question: calculate the maximum number of cycles of a string.

Analysis: DP, KMP, String. The KMP algorithm is used here.

The next function of KMP jumps to the recursive structure position of the nearest string (the value of the string element is 0 ~ Len-1 );

The KMP process shows that:

If a circular section exists, s [0 ~ Next [Len]-1] and S [Len-next [Len] ~ Len-1] matching;

Then s [next [Len] ~ The len-1] is the loop section (and the smallest), otherwise next [Len] is 0;

Therefore, the maximum number of loops is Len/(LEN-next [Len]), and the minimum cycle is s [next [Len] ~. Len-1].

Note: Powerful KMP (⊙ _ ⊙ ).

#include <iostream>#include <cstdlib>#include <cstring>#include <cstdio>using namespace std;char str[1000004];int  next[1000004];void getnext( char *T, int L )  {      next[0] = -1;      int i = 0,j = -1;      while ( i < L ) {          if ( j == -1 || T[i] == T[j] ) {              i ++; j ++;              next[i] = j;          }else j = next[j];      }  }  int main(){while ( scanf("%s",str) && strcmp( str, "." ) ) {int len = strlen(str);   getnext( str, len );  printf("%d\n",len/(len-next[len]));}return 0;}