洛谷P3763 [Tjoi2017]DNA 【后缀数组】

题目链接

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;

}
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洛谷P3763 [Tjoi2017]DNA 【后缀数组】

题目链接

题解

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