poj 2774 Long Long Message

 第一个后缀数组，拍模版……

/*
 * Author: stormdpzh
 * Created Time: 2012/7/22 14:22:35
 * File Name: poj_2774.cpp
 */
#include <iostream>
#include <cstdio>
#include <sstream>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <algorithm>
#include <functional>

#define sz(v) ((int)(v).size())
#define rep(i, n) for(int i = 0; i < n; i++)
#define repf(i, a, b) for(int i = a; i <= b; i++)
#define repd(i, a, b) for(int i = a; i >= b; i--)
#define out(n) printf("%d\n", n)
#define mset(a, b) memset(a, b, sizeof(a))
#define wh(n) while(1 == scanf("%d", &n))
#define whz(n) while(1 == scanf("%d", &n) && n != 0)
#define lint long long

using namespace std;

const int MaxN = 200005;

char s[MaxN];
int n;
int sa[MaxN], height[MaxN], rank[MaxN], tmp[MaxN], top[MaxN];

void makesa()
{
    int na = n < 256 ? 256 : n;
    mset(top, 0);
    rep(i, n) top[rank[i] = s[i] & 0xff]++;
    repf(i, 1, na - 1) top[i] += top[i - 1];
    rep(i, n) sa[--top[rank[i]]] = i;
    for(int len = 1; len < n; len <<= 1) {
        int j;
        rep(i, n) {
            j = sa[i] - len;
            if(j < 0) j += n;
            tmp[top[rank[j]]++] = j;
        }
        sa[tmp[top[0] = 0]] = j = 0;
        repf(i, 1, n - 1) {
            if(rank[tmp[i]] != rank[tmp[i - 1]] || rank[tmp[i] + len] != rank[tmp[i - 1] + len])
                top[++j] = i;
            sa[tmp[i]] = j;
        }
        memcpy(rank, sa, n * sizeof(int));
        memcpy(sa, tmp, n * sizeof(int));
        if(j >= n - 1) break;
    }
}

void lcp()
{
    int i, j, k;
    for(j = rank[height[i = k = 0] = 0]; i < n - 1; i++, k++)
        while(k >= 0 && s[i] != s[sa[j - 1] + k]) {
            height[j] = (k--);
            j = rank[sa[j] + 1];
        }
}

bool check(int i, int len)
{
    if(sa[i] < len && sa[i - 1] < len) return false;
    if(sa[i] > len && sa[i - 1] > len) return false;
    return true;
}

int main()
{
    while(1 == scanf("%s", s)) {
        int len = strlen(s);
        s[len] = 2;
        n = len;
        scanf("%s", s + n + 1);
        n = strlen(s);
        s[n] = 1;
        n++;
        makesa();
        lcp();
        int res = 0;
        rep(i, n) if(res < height[i] && check(i, len))
            res = height[i];
        printf("%d\n", res);
    }         
    return 0;
}