- 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