poj2217 Secretary 后缀数组

Posted 2020-10-20 poorpool

#include <iostream>
#include <cstring>
#include <string>
#include <cstdio>
using namespace std;
int T, n, m, p, len, r[20005], c[20005], x[20005], y[20005], sa[20005];
int rank[20005], ans, hei[20005];
string s, t;
void getSa(){
    r[n++] = 0;
    for(int i=0; i<m; i++)  c[i] = 0;
    for(int i=0; i<n; i++)  c[x[i]=r[i]]++;
    for(int i=1; i<m; i++)  c[i] += c[i-1];
    for(int i=n-1; i>=0; i--)   sa[--c[x[i]]] = i;
    for(int j=1; p<n; j*=2, m=p){
        p = 0;
        for(int i=n-j; i<n; i++)    y[p++] = i;
        for(int i=0; i<n; i++)  if(sa[i]>=j)    y[p++] = sa[i] - j;
        for(int i=0; i<m; i++)  c[i] = 0;
        for(int i=0; i<n; i++)  c[x[y[i]]]++;
        for(int i=1; i<m; i++)  c[i] += c[i-1];
        for(int i=n-1; i>=0; i--)   sa[--c[x[y[i]]]] = y[i];
        swap(x, y);
        p = 1;
        x[sa[0]] = 0;
        for(int i=1; i<n; i++)
            if(y[sa[i-1]]==y[sa[i]] && y[sa[i-1]+j]==y[sa[i]+j])
                x[sa[i]] =  p - 1;
            else
                x[sa[i]] = p++;
    }
    n--;
}
void getLcp(){
    int h=0;
    for(int i=1; i<=n; i++) rank[sa[i]] = i;
    for(int i=0; i<n; i++){
        if(h)   h--;
        int j=sa[rank[i]-1];
        while(r[i+h]==r[j+h])   h++;
        hei[rank[i]] = h;
    }
}//构建height数组
int main(){
    cin>>T;
    getline(cin, s);
    while(T--){
        getline(cin, s);
        getline(cin, t);
        len = s.size();
        s = s + "$" + t;
        n = s.size();
        m = 128;
        ans = p = 0;
        for(int i=0; i<n; i++)  r[i] = (int)s[i];
        getSa();
        getLcp();
        for(int i=2; i<=n; i++)
            if((sa[i-1]<len)^(sa[i]<len))
                ans = max(ans, hei[i]);
        printf("Nejdelsi spolecny retezec ma delku %d.\n", ans);
    }
    return 0;
}