Longest Repeated Substring zoj3199

比论文上的那题简单，直接由高到低枚举长度，发现重复超过一次的就是答案

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <algorithm>
#include <vector>
#include <cstring>
#include <stack>
#include <cctype>
#include <utility>   
#include <map>
#include <string>  
#include <climits> 
#include <set>
#include <string>    
#include <sstream>
#include <utility>   
#include <ctime>

using std::priority_queue;
using std::vector;
using std::swap;
using std::stack;
using std::sort;
using std::max;
using std::min;
using std::pair;
using std::map;
using std::string;
using std::cin;
using std::cout;
using std::set;
using std::queue;
using std::string;
using std::istringstream;
using std::make_pair;
using std::getline;
using std::greater;
using std::endl;
using std::multimap;
using std::deque;

typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int, int> PAIR;
typedef multimap<int, int> MMAP;

const int MAXN(50010);
const int SIGMA_SIZE(26);
const int MAXM(110);
const int MAXE(300010);
const int MAXH(18);
const int INFI((INT_MAX-1) >> 1);
const int MOD(2520);
const ULL BASE(31);
const ULL LIM(1000000000000000ull);


struct SA
{
    char S[MAXN];
    int sa[MAXN], t1[MAXN], t2[MAXN], cnt[MAXN], len, M;
    void init(int tl, int tm = 128)
    {
        len = tl;
        M = tm;
        int *p1 = t1;
        int *p2 = t2;
        for(int i = 0; i < M; ++i) cnt[i] = 0;
        for(int i = 0; i <= len; ++i) ++cnt[p1[i] = S[i]];
        for(int i = 1; i < M; ++i) cnt[i] += cnt[i-1];
        for(int i = len; i >= 0; --i) sa[--cnt[p1[i]]] = i;
        int temp = 1;
        for(int k = 1; temp <= len; k <<= 1)
        {
            temp = 0;
            for(int i = len-k+1; i <= len; ++i) p2[temp++] = i;
            for(int i = 0; i <= len; ++i)
                if(sa[i] >= k)
                    p2[temp++] = sa[i]-k;
            
            for(int i = 0; i < M; ++i) cnt[i] = 0;
            for(int i = 0; i <= len; ++i) ++cnt[p1[p2[i]]];
            for(int i = 1; i < M; ++i) cnt[i] += cnt[i-1];
            for(int i = len; i >= 0; --i) sa[--cnt[p1[p2[i]]]] = p2[i];
            swap(p1, p2);
            temp = 1;
            p1[sa[0]] = 0;
            for(int i = 1; i <= len; ++i)
                p1[sa[i]] = p2[sa[i-1]] == p2[sa[i]] && p2[sa[i-1]+k] == p2[sa[i]+k]? temp-1: temp++;
            M = temp;
        }
    }
    int rank[MAXN], height[MAXN];
    void getHeight()
    {
        int k = 0;
        for(int i = 0; i <= len; ++i)
            rank[sa[i]] = i;
        for(int i = 0; i < len; ++i)
        {
            if(k) --k;
            int j = sa[rank[i]-1];
            while(S[i+k] == S[j+k]) ++k;
            height[rank[i]] = k;
        }
    }

    int Log[MAXN];
    int table[MAXH][MAXN];

    void initLog()
    {
        Log[0] = -1;
        for(int i = 1; i < MAXN; ++i)
            Log[i] = (i&(i-1))? Log[i-1]: Log[i-1]+1;
    }

    void initRMQ()
    {
        for(int i = 1; i <= len; ++i)
            table[0][i] = height[i];
        for(int i = 1; (1 << i) <= len; ++i)
            for(int j = 1; j+(1 << i)-1 <= len; ++j)
                table[i][j] = min(table[i-1][j], table[i-1][j+(1 << (i-1))]);
    }

    int lcp(int a, int b)
    {
        a = rank[a];
        b = rank[b];
        if(a > b) swap(a, b);
        ++a;
        int temp = Log[b-a+1];
        return min(table[temp][a], table[temp][b-(1 << temp)+1]);
    }
};

SA sa;

int main()
{
	sa.initLog();
	int TC;
	scanf("%d", &TC);
	while(TC--)
	{
		scanf("%s", sa.S);
		int len = strlen(sa.S);
		sa.init(len);
		sa.getHeight();
		sa.initRMQ();
		int ans = len/2+1;
		for(; ans >= 1; --ans)
		{
			bool flag(false);
			int lim = len-ans;
			for(int i = 0; i <= lim; i += ans)
			{
				int temp = sa.lcp(i, i+ans);
				if(temp >= ans)
				{
					flag = true;
					break;
				}
				int ti = i-(ans-temp%ans);
				if(ti >= 0)
				{
					temp = sa.lcp(ti, ti+ans);
					if(temp >= ans)
					{
						flag = true;
						break;
					}
				}
			}
			if(flag)
				break;
		}
		printf("%d\n", ans);
	}
	return 0;
}