首页 > 代码库 > poj 2406 Power Strings

poj 2406 Power Strings

题目链接:http://poj.org/problem?id=2406

 

思路

1.理解Kmp算法的next数组的意义;

2.对于字符A[i],i-next[i]等价于在字符串中存在一个长度为i-next[i]的重复子串;

3.当 i % (i - next[i]) == 0 等价于字符串由 (i/(i-next[i])) 个长度为 i - next[i]的子串连接组成;

 

代码: 

#include <iostream>#include <string>using namespace std;const int MAX_N = 1000000 + 10;char S[MAX_N];int Next[MAX_N];int GetNext(char P[], int next[]){    int i = 0, j = -1;    int len = strlen(P);    if (len <= 0)        return 0;    next[0] = -1;    while (i <= len)    {        if (j == -1 || P[i] == P[j])            next[++i] = ++j;        else            j = next[j];    }}int main(){    int len;    int lenSubstr;    while (scanf("%s", S) != EOF && strcmp(S, "."))    {        len = strlen(S);        GetNext(S, Next);        lenSubstr = len - Next[len];        if (len % lenSubstr == 0)            printf("%d\n", len / lenSubstr);        else            printf("1\n");    }    return 0;}

 

poj 2406 Power Strings