相似子串 bzoj3230

http://www.lydsy.com/JudgeOnline/problem.php?id=3230

后缀数组

#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>
#include <bitset>
#include <iomanip>
//#pragma comment(linker, "/STACK:102400000,102400000")

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::stringstream;
using std::make_pair;
using std::getline;
using std::greater;
using std::endl;
using std::multimap;
using std::deque;
using std::unique;
using std::lower_bound;
using std::random_shuffle;
using std::bitset;
using std::upper_bound;
using std::multiset;
using std::ios;
using std::make_heap;
using std::push_heap;
using std::pop_heap;

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

const int MAXN(100010);
const int MAXM(310);
const int MAXE(310);
const int MAXK(6);
const int HSIZE(13131);
const int SIGMA_SIZE(26);
const int MAXH(18);
const int INFI((INT_MAX-1) >> 1);
const ULL BASE(31);
const LL LIM(1e13);
const int INV(-10000);
const int MOD(1000000007);
const double EPS(1e-7);
const LF PI(acos(-1.0));

template<typename T> inline void checkmax(T &a, T b){if(b > a) a = b;}
template<typename T> inline void checkmin(T &a, T b){if(b < a) a = b;}
template<typename T> inline T ABS(const T &a){return a < 0? -a: a;}

int Log[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;
}

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, *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], hei[MAXN]; 
	void getHei()
	{
		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;
			hei[rank[i]] = k;
		}
	}
	int dp[MAXH][MAXN];
	void initRMQ()
	{
		for(int i = 1; i <= len; ++i)
			dp[0][i] = hei[i];
		for(int i = 1; (1 << i) <= len; ++i)
			for(int j = 1; j+(1 << i)-1 <= len; ++j)
				dp[i][j] = min(dp[i-1][j], dp[i-1][j+(1 << (i-1))]);
	}
	int lcp(int a, int b)
	{
		if(a == b) return len-a;
		a = rank[a];
		b = rank[b];
		if(a > b) swap(a, b);
		++a;
		int temp = Log[b-a+1];
		return min(dp[temp][a], dp[temp][b-(1 << temp)+1]);
	}
} sa1, sa2;

LL rec[MAXN];

int main()
{
	initLog();
	int n, Q;
	scanf("%d%d", &n, &Q);
	scanf("%s", sa1.S);
	for(int i = 0; i < n; ++i) sa2.S[i] = sa1.S[n-i-1];
	sa2.S[n] = '\0';
	sa1.init(n);
	sa2.init(n);
	sa1.getHei();
	sa2.getHei();
	sa1.initRMQ();
	sa2.initRMQ();
	for(int i = 1; i <= n; ++i) rec[i] = rec[i-1]+(n-sa1.sa[i]-sa1.hei[i]);
	LL q1, q2;
	for(int i = 0; i < Q; ++i)
	{
		scanf("%lld%lld", &q1, &q2);
		int i1 = lower_bound(rec, rec+1+n, q1)-rec;
		int i2 = lower_bound(rec, rec+1+n, q2)-rec;
		if(i1 > n || i2 > n)
		{
			printf("-1\n");
			continue;
		}
		int l1 = (n-sa1.sa[i1])-(rec[i1]-q1);
		int l2 = (n-sa1.sa[i2])-(rec[i2]-q2);
		LL a = min(sa1.lcp(sa1.sa[i1], sa1.sa[i2]), min(l1, l2));
		LL b = min(sa2.lcp(n-1-(sa1.sa[i1]+l1-1), n-1-(sa1.sa[i2]+l2-1)), min(l1, l2));
		printf("%lld\n", a*a+b*b);
	}
	return 0;
}