洛谷P3763 [Tjoi2017]DNA 【后缀数组】

题目链接

洛谷P3763

题解

后缀数组裸题

在BZOJ被卡常到哭QAQ

#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<map>
#define Redge(u) for (int k = h[u],to; k; k = ed[k].nxt)
#define REP(i,n) for (register int i = 1; i <= (n); i++)
#define mp(a,b) make_pair<int,int>(a,b)
#define cls(s) memset(s,0,sizeof(s))
#define cp pair<int,int>
#define LL long long int
#define res register
using namespace std;
const int maxn = 200005,maxm = 100005,INF = 1000000000;
inline int read(){
	res int out = 0,flag = 1; res char c = getchar();
	while (c < 48 || c > 57){if (c == '-') flag = -1; c = getchar();}
	while (c >= 48 && c <= 57){out = (out << 3) + (out << 1) + c - 48; c = getchar();}
	return out * flag;
}
char s[maxn],s2[maxn];
int sa[maxn],rank[maxn],height[maxn],bac[maxn],t1[maxn],t2[maxn],mn[maxn][18],n,m;
int bin[50],Log[maxn],lenp,lent;
inline void getsa(){
	int *x = t1,*y = t2; m = 255;
	for (res int i = 0; i <= m; i++) bac[i] = 0;
	for (res int i = 1; i <= n; i++) bac[x[i] = s[i]]++;
	for (res int i = 1; i <= m; i++) bac[i] += bac[i - 1];
	for (res int i = n; i; i--) sa[bac[x[i]]--] = i;
	for (res int k = 1; k <= n; k <<= 1){
		int p = 0;
		for (res int i = n - k + 1; i <= n; i++) y[++p] = i;
		for (res int i = 1; i <= n; i++) if (sa[i] - k > 0) y[++p] = sa[i] - k;
		for (res int i = 0; i <= m; i++) bac[i] = 0;
		for (res int i = 1; i <= n; i++) bac[x[y[i]]]++;
		for (res int i = 1; i <= m; i++) bac[i] += bac[i - 1];
		for (res int i = n; i; i--) sa[bac[x[y[i]]]--] = y[i];
		swap(x,y);
		x[sa[1]] = p = 1;
		for (res 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] ? p : ++p);
		if (p >= n) break;
		m = p;
	}
	for (res int i = 1; i <= n; i++) rank[sa[i]] = i;
	for (res int i = 1,k = 0; i <= n; i++){
		if (k) k--;
		int j = sa[rank[i] - 1];
		while (i + k <= n && j + k <= n && s[i + k] == s[j + k]) k++;
		height[rank[i]] = k;
	}
	for (res int i = 1; i <= n; i++) mn[i][0] = height[i];
	REP(j,17) REP(i,n){
		if (i + bin[j] - 1 > n) break;
		mn[i][j] = min(mn[i][j - 1],mn[i + bin[j - 1]][j - 1]);
	}
}
inline int lcp(int x,int y){
	int l = rank[x],r = rank[y];
	if (l > r) swap(l,r); l++;
	int t = Log[r - l + 1];
	return min(mn[l][t],mn[r - bin[t] + 1][t]);
}
void solve(){
	int ans = 0;
	for (res int i = 1; i <= lenp - lent + 1; i++){
		res int j = 1,tmp,cnt = 3;
		while (cnt && j <= lent){
			tmp = lcp(i + j - 1,lenp + 1 + j);
			if (!tmp) j++,cnt--;
			else j += tmp;
		}
		if (j <= lent){
			j += lcp(i + j - 1,lenp + 1 + j);
		}
		if (j > lent){
			ans++;
		}
	}
	printf("%d\n",ans);
}
int main(){
	bin[0] = 1; REP(i,25) bin[i] = bin[i - 1] << 1;
	Log[0] = -1; REP(i,200000) Log[i] = Log[i >> 1] + 1;
	int T = read();
	while (T--){
		scanf("%s",s + 1); lenp = strlen(s + 1);
		s[lenp + 1] = 1; s[lenp + 2] = '\0';
		scanf("%s",s2 + 1); lent = strlen(s2 + 1);
		strcat(s + 1,s2 + 1);
		n = lenp + 1 + lent;
		getsa();
		solve();
	}
	return 0;
}