http://poj.org/problem?id=2774
题解:后缀数组+最长公共子串
/*
*@Author: STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
#define endl "\n"
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=200000+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,p,l,u,v;
int ans,cnt,flag,temp,sum;
int r[N],c[N],x[N],y[N],sa[N],ra[N],height[N];
char str1[N],str2[N];
struct node{};
void SA(int n,int m){
for(int i=0;i<=m;i++)c[i]=0;
for(int i=1;i<=n;i++)c[x[i]=r[i]]++;
for(int i=1;i<=m;i++)c[i]+=c[i-1];
for(int i=n;i>=1;i--)sa[c[x[i]]--]=i;
for(int k=1;k<=n;k<<=1){
int num=0;
for(int i=n-k+1;i<=n;i++)y[++num]=i;
for(int i=1;i<=n;i++)if(sa[i]>k)y[++num]=sa[i]-k;
for(int i=0;i<=m;i++)c[i]=0;
for(int i=1;i<=n;i++)c[x[i]]++;
for(int i=1;i<=m;i++)c[i]+=c[i-1];
for(int i=n;i>=1;i--)sa[c[x[y[i]]]--]=y[i],y[i]=0;
swap(x,y);
x[sa[1]]=1;
num=1;
for(int i=2;i<=n;i++)
x[sa[i]]=(y[sa[i]]==y[sa[i-1]]&&y[sa[i]+k]==y[sa[i-1]+k])?num:++num;
if(num==n)
break;
m=num;
}
}
void getheight(int n){
int k=0;
for(int i=1;i<=n;i++)ra[sa[i]]=i;
for(int i=1;i<=n;i++){
if(k)k--;
int j=sa[ra[i]-1];
while(r[i+k]==r[j+k])k++;
height[ra[i]]=k;
}
}
int main()
{
#ifdef DEBUG
freopen("input.in", "r", stdin);
//freopen("output.out", "w", stdout);
#endif
//ios::sync_with_stdio(false);
//cin.tie(0);
//cout.tie(0);
//scanf("%d",&t);
//while(t--){
//scanf("%d",&n);
while(~scanf("%s%s",str1+1,str2+1)){
int len1=strlen(str1+1);
int len2=strlen(str2+1);
for(int i=1;i<=len1;i++)r[i]=str1[i]-'a'+1;
r[len1+1]=27;
for(int i=1;i<=len2;i++)r[i+len1+1]=str2[i]-'a'+1;
int len=len1+len2+2;
r[len]=0;
SA(len,27);
getheight(len);
ans=-INF;
for(int i=2;i<=len;i++){
if((sa[i]<=len1)!=(sa[i-1]<=len1)){
ans=max(ans,height[i]);
}
}
cout<<ans<<endl;
}
//}
#ifdef DEBUG
printf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif
//cout << "Hello world!" << endl;
return 0;
}