hdu1403 求最长公共前缀 后缀数组

#include<stdio.h>
#include<string>
#include<map>
#include<vector>
#include<cmath>
#include<stdlib.h>
#include<string.h>
#include<algorithm>
#include<iostream>
using namespace std;
#define rep0(i,n) for(int i=0;i<n;i++)
#define rep(i,j,k) for(int i=j;i<k;i++)
const int N=2e5+10;
const int MOD=1e9+7;
int n,m,k,up;
char s[N],ss[N];
int cnt[N],f[N],r[N],sa[N],sr[N],height[N];
/*
sa[i] 排第i的下标


f[i] 下标为i的排名

*/
void getSa(){
    up=0;
    int len=strlen(s);
    rep0(i,len) ss[i]=s[i]-'*',up=max((int)ss[i],up);
    up++;
    rep0(i,up) cnt[i]=0;
    rep0(i,len) cnt[  f[i]=ss[i]    ]++;
    rep(i,1,up) cnt[i]+=cnt[i-1];

    for(int i=len-1;i>=0;i--)   sa[   --cnt[f[i]]  ]=i;

    int d=1,p=0;
    while(d<len){
        for(int i=len-d;i<len;i++) sr[p++]=i;
        rep0(i,len) if(sa[i]>=d) sr[p++]=sa[i]-d;
        rep0(i,up) cnt[i]=0;
        rep0(i,len) cnt[f[sr[i]]]++;
       rep(i,1,up) cnt[i]+=cnt[i-1];
        for(int i=len-1;i>=0;i--) sa[--cnt[f[sr[i]]]   ]=sr[i];

        swap(f,r);
        p=0;
        f[sa[0]]=p++;
        rep0(i,len-1){
            if(sa[i]+d<len &&sa[i+1]+d<len && r[sa[i]]==r[sa[i+1]] && r[sa[i]+d]==r[sa[i+1]+d])
            f[sa[i+1]]=p-1;
            else f[sa[i+1]]=p++;
        }
        d*=2;up=p;p=0;
    }
    rep0(i,len) f[sa[i]]=i;
}
void getH(){
    int len=strlen(s);
    int p=0;
    for(int i=0;i<len;i++){
        if(f[i]==0) continue;
        int k=sa[f[i]-1];
        while(k+p<len && i+p<len && s[k+p]==s[i+p]) p++;
        height[i]=p;
        p=max(0,p-1);
    }
}
void solve(char *s1,char *s2){
    int len=strlen(s1);
    strcpy(s,s1);
    strcpy(s+len,"*");
    strcpy(s+len+1,s2);

    getSa();

    getH();
    int len2=strlen(s);
    int res=0;
    for(int i=0;i<len2;i++){
        int k=f[i];
        if(k==0) continue;
        int j=sa[k-1];
        if( (i<len && j>len)   ||    (i>len && j<len)   ) res=max(res,height[i]);
    }
    printf("%d\n",res);
}
int main(){
#ifndef ONLINE_JUDGE
  freopen("aaa","r",stdin);
#endif
    int T;
    char s1[N],s2[N];
    while(~scanf("%s%s",s1,s2)){
        solve(s1,s2);
    }
    return 0;
}