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题意:给你一个字符串,然后让你看看有没有前缀的循环节大于1,如果有,输出前缀的长度和循环节大小。
思路:判断字符串是否是周期性字符串:i % (i - Next[i] )==0 ,循环节长度 i - Next[i] ,循环节出现次数为 i / (i - Next[i])。
AC Code:
#include<iostream>
#include<cstring>
#include<queue>
#include<map>
#include<stack>
#include<cmath>
#include<cstdio>
#include<iomanip>
#include<sstream>
#include<algorithm>
using namespace std;
#define read(x) scanf("%d",&x)
#define Read(x,y) scanf("%d%d",&x,&y)
#define sRead(x,y,z) scanf("%d%d%d",&x,&y,&z)
#define gc(x) scanf(" %c",&x);
#define mmt(x,y) memset(x,y,sizeof x)
#define write(x) printf("%d\n",x)
#define INF 0x3f3f3f3f
#define ll long long
#define mod 998244353
#define pdd pair<double,double>
const int N = 1000;
const int M= 1e6;
char c[M+5],s[M+5];
int m;
int Next[M+5];
void kmp_pre()
{
int i = 0;
int j = Next[0] = -1;
while(i < m){
while(j != -1 && c[i]!=c[j]) j = Next[j];
Next[++i] = ++j;
}
}
int main()
{
int k = 1;
while(~scanf("%d",&m)&&m){
mmt(Next,0);
scanf("%s",c);
printf("Test case #%d\n",k++);
kmp_pre();
for(int i = 1;i <= m;++i){
if(i%(i - Next[i]) == 0&&i / (i - Next[i])!=1){
cout<<i<<" "<<i / (i - Next[i])<<endl;
}
}
puts("");
}
}