- Power Strings (字符串哈希) (KMP)

https://www.cnblogs.com/widsom/p/8058358.htm　　（详细解释）

//#include<bits/stdc++.h>
#include<vector>
#include<cstdio>
#include<cstring>
#include<iostream>
#define ull unsigned long long
using namespace std;
const int maxn=1e6+;
char a[maxn];
ull b[maxn];
ull c[maxn];
int main()
{
    b[]=; ull d=;
    for(int i=;i<=maxn;i++) b[i]=b[i-]*d;
    while()
    {
        scanf("%s",a+); int n=strlen(a+);
        if(n== && a[]=='.') break;
        for(int i=;i<=n;i++) c[i]=c[i-]*d+(a[i]-'a'+);
        vector<int> vs; for(int i=;i<=n;i++)  { if(n%i==) vs.push_back(i); }
        int ans=;
        for(int i=;i<vs.size();i++)
        {
            int flag=;
            for(int j=*vs[i];j<=n;j+=vs[i])
            {
                ull x=c[j]-c[j-vs[i]]*b[vs[i]];
                if(x!=c[vs[i]]) {flag=; }
            }
            if(flag) {ans=n/vs[i]; break; }
        }
        printf("%d\n",ans);
    }
}

//#include<bits/stdc++.h>
#include<vector>
#include<cstdio>
#include<cstring>
#include<iostream>
#define ull unsigned long long
using namespace std;
const int maxn=1e6+;
char ss[maxn];
int nt[maxn];
int KMP()
{
    int l=strlen(ss);
    nt[]=-;
    for (int i = ; i < l; ++i) {
        int j = nt[i-];
        while(ss[j+] != ss[i] && j >= ) j = nt[j];
        if(ss[j+] == ss[i]) nt[i] = j+;
        else nt[i] = -;
    }
    for(int i=;i<l;i++)
    {
        cout<<nt[i]<<endl;
    }
    int k=l-(nt[l-]+);
    if(l%k==) return l/k;
    else return ;
}
int main()
{

    while()
    {
        scanf("%s",ss); int n=strlen(ss);
        if(n== &&ss[]=='.') break;
        printf("%d\n",KMP());
    }
}

KMP

//#include<bits/stdc++.h>
#include<vector>
#include<cstdio>
#include<cstring>
#include<iostream>
#define ull unsigned long long
using namespace std;
const int maxn=1e6+;
char ss[maxn];
int nt[maxn];
int KMP()
{
    int l=strlen(ss);  // ss
    //int t=strlen(tt);
    nt[]=-;
    int num=;
    for(int i=,j=-;i<l;)
    {
        if(j==-||ss[i]==ss[j])
        {
            nt[i]=j; // next[1]=
            i++; j++;

        }
        else
            j=nt[j];
    }
    int k=l-(nt[l-]+);
    if(l%k==) return l/k;
    else return ;
}
int main()
{

    while()
    {
        scanf("%s",ss); int n=strlen(ss);
        if(n== &&ss[]=='.') break;
        printf("%d\n",KMP());
    }
}

KMP

桶排序

#include <iostream>
#include <vector>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define rank rk
using namespace std;

typedef long long LL;

const int maxn = , M = ;
// sa[1-n] -> 0->n-1;
int sa[maxn], rank[maxn], height[maxn];

int wa[maxn], wb[maxn], wv[maxn], cnt[maxn];
void SA(int *r, int n, int m) {
    int *x = wa, *y = wb;
    for(int i = ; i < m; i++) cnt[i] = ;
    for(int i = ; i < n; i++) cnt[x[i] = r[i]]++;
    for(int i = ; i < m; i++) cnt[i] += cnt[i - ];
    for(int i = n - ; i >= ; i--) sa[--cnt[x[i]]] = i;
    for(int j = ; j < n; j <<= ) {
        int p = ;
        for(int i = n - j; i < n; i++) y[p++] = i;
        for(int i = ; i < n; i++) if(sa[i] >= j) y[p++] = sa[i] - j;
        for(int i = ; i < n; i++) wv[i] = x[y[i]];
        for(int i = ; i < m; i++) cnt[i] = ;
        for(int i = ; i < n; i++) cnt[wv[i]]++;
        for(int i = ; i < m; i++) cnt[i] += cnt[i - ];
        for(int i = n - ; i >= ; i--) sa[--cnt[wv[i]]] = y[i];
        swap(x, y);
        p = ; x[sa[]] = ;
        for(int i = ; i < n; i++)
            x[sa[i]] = y[sa[i - ]] == y[sa[i]] && y[sa[i - ] + j] == y[sa[i] + j] ? p -  : p++;
        if(p >= n) break;
        m = p;
    }
}

void calcHeight(int *r, int n) {
    int i, j, k;
    for(i = j = k = ; i < n; height[rank[i++]] = k)
        for(k ? k-- : , j = sa[rank[i] - ]; r[i + k] == r[j + k]; k++);
}

int n, s[maxn];
char str[maxn];
int lg[maxn];
int main() {
    for(int i=;i<maxn;i++){lg[i]=lg[i>>]+;}
    while()
    {
        scanf("%s", str); n = strlen(str);
        if(n== && str[]=='.') break;
        for(int i = ; i < n; i++) s[i] = str[i]; s[n] = ;
        SA(s, n + , M);
        for(int i = ; i <= n; i++) rank[sa[i]] = i;
        calcHeight(s, n);
        int ans = ;
        for (int i = ; i <= n; ++i) {
            if(n%i == ) {
                if(rank[]-rank[i] ==  && height[rank[]] == n-i) {
                    ans = n/i;
                    break;
                }
            }
        }
        printf("%d\n",ans);
    }
    return ;
}

会T

DC3