poj2774 后缀数组2个字符串的最长公共子串

/*
 * Author:  sweat123
 * Created Time:  2016/7/9 19:39:27
 * File Name: main.cpp
 */
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<cmath>
#include<string>
#include<vector>
#include<cstdio>
#include<time.h>
#include<cstring>
#include<iostream>
#include<algorithm>
#define INF 1<<30
#define MOD 1000000007
#define ll long long
#define lson l,m,rt<<1
#define key_value ch[ch[root][1]][0]
#define rson m+1,r,rt<<1|1
#define pi acos(-1.0)
using namespace std;
const int MAXN = 200010;
char s1[MAXN],s2[MAXN];
int n,r[MAXN],height[MAXN],Rank[MAXN],wa[MAXN],wb[MAXN],wc[MAXN];
int sa[MAXN];
void da(int *r,int *sa,int n,int m){
    int *x = wa,*y = wb;
    for(int i = 0; i < m; i++)wc[i] = 0;
    for(int i = 0; i < n; i++)wc[x[i] = r[i]] ++;
    for(int i = 0; i < m; i++)wc[i] += wc[i-1];
    for(int i = n - 1; i >= 0; i--)sa[--wc[x[i]]] = i;
    for(int p = 1,k = 1; p < n; k <<= 1, m = p){
        p = 0;
        for(int i = n - k; i < n; i++)y[p++] = i;
        for(int i = 0; i < n; i++)if(sa[i] >= k)y[p++] = sa[i] - k;
        for(int i = 0; i < m; i++)wc[i] = 0;
        for(int i = 0; i < n; i++)wc[x[y[i]]] ++;
        for(int i = 0; i < m; i++)wc[i] += wc[i-1];
        for(int i = n - 1; i >= 0; i--)sa[--wc[x[y[i]]]] = y[i];
        swap(x,y);
        p = 1;
        x[sa[0]] = 0;
        for(int i = 1; i < n; i++){
            x[sa[i]] = (y[sa[i]] == y[sa[i-1]] && y[sa[i]+k] == y[sa[i-1]+k])?p-1:p++;
        }   
    }   
}
void calheight(int *r,int *sa,int n){
    for(int i = 1; i <= n; i++)Rank[sa[i]] = i;
    int j,k;
    k = 0;
    for(int i = 0; i < n; height[Rank[i++]] = k){
        for(k?k--:0,j = sa[Rank[i] - 1]; r[i+k] == r[j+k]; k++);
    }   
}
void solve(int len1,int len2){
    int ans = 0,l,r;
    for(int i = 1; i <= n; i++){
        if(height[i] > ans){
            l = sa[i-1];
            r = sa[i];
            if(l + height[i] - 1 < len1 && r > len1)ans = max(ans,height[i]);
            if(r + height[i] - 1 < len1 && l > len1)ans = max(ans,height[i]);
        }
    }
    printf("%d\n",ans);
}
int main(){
    while(~scanf("%s",s1)){
        scanf("%s",s2);
        int len1 = strlen(s1);
        int len2 = strlen(s2);
        n = 0;
        for(int i = 0; i < len1; i++){
            r[i] = s1[i];
        }   
        r[len1] = 1;
        for(int i = 0; i < len2; i++){
            r[i + len1 + 1] = s2[i];   
        }
        n = len1 + len2 + 1;
        r[n] = 0;
        da(r,sa,n+1,128);
        calheight(r,sa,n);
        solve(len1,len2);
    }
    return 0;
}