poj1961

poj1961
主要是考察对next数组的理解，
abaabaabaaba
abaabaaba
abaabaaba
错开的部分便是循环节

7月29日更

如果n%(n-kmp[k])==0,那么n-kmp[k]便是循环节的长度，我来解释一下为什么

 

#include<iostream>
#include<cstdio>
#include<queue>
#include<algorithm>
#include<cmath>
#include<ctime>
#include<set>
#include<map>
#include<stack>
#include<cstring>
#define inf 2147483647
#define ls rt<<1
#define rs rt<<1|1
#define lson ls,nl,mid,l,r
#define rson rs,mid+1,nr,l,r
#define N 1000010
#define For(i,a,b) for(int i=a;i<=b;i++)
#define p(a) putchar(a)
#define g() getchar()

using namespace std;
int kmp[N];
int n,k;
char a[N];
int cnt;
void in(int &x){
    int y=1;
    char c=g();x=0;
    while(c<'0'||c>'9'){
        if(c=='-')y=-1;
        c=g();
    }
    while(c<='9'&&c>='0'){
        x=(x<<1)+(x<<3)+c-'0';c=g();
    }
    x*=y;
}
void o(int x){
    if(x<0){
        p('-');
        x=-x;
    }
    if(x>9)o(x/10);
    p(x%10+'0');
}

void clear(){
    memset(kmp,0,sizeof(kmp));
    k=0;
}

int main(){
    while(cin>>n&&n){
        clear();
        cin>>(a+1);
        For(i,2,n){
            while(k&&a[i]!=a[k+1])
                k=kmp[k];
            if(a[k+1]==a[i])
                k++;
            kmp[i]=k;
        }
    cout<<"Test case #"<<++cnt<<endl;
    For(i,2,n)
        if(kmp[i]>0&&i%(i-kmp[i])==0){
            o(i);p(' ');o(i/(i-kmp[i]));p('\n');
        }
    p('\n');
    }
    return 0;       
}