宠物收养所

题目描述

思路

代码

#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <cmath>

const int MAX = 8e4 + 5, mod = 1e6;
int n, m, inf = 0x3f3f3f3f;
int ans, rt, tot;
bool flag;
struct Node {
	int lc, rc, key, pri, cnt, size;
	#define lc(x) t[x].lc
	#define rc(x) t[x].rc
	#define key(x) t[x].key
	#define pri(x) t[x].pri
	#define cnt(x) t[x].cnt
	#define size(x) t[x].size
} t[MAX];

inline int read() {
	int s = 0, f = 1;
	char ch = getchar();
	while (ch < '0' || ch > '9') {
		if (ch == '-') f = -1;
		ch = getchar();
	}
	while (ch >= '0' && ch <= '9') s = s * 10 + ch - '0', ch = getchar();
	return s * f;
}
void write(int x) {
	if (x > 9) write(x / 10);
	putchar(x % 10 + '0');
}
void update(int r) { size(r) = size(lc(r)) + size(rc(r)) + cnt(r); }
void zig(int &r) {
	int s = lc(r);
	lc(r) = rc(s);
	rc(s) = r;
	size(s) = size(r);
	update(r);
	r = s;
}
void zag(int &r) {
	int s = rc(r);
	rc(r) = lc(s);
	lc(s) = r;
	size(s) = size(r);
	update(r);
	r = s;
}
void insert(int &r, int k) {
	if (!r) {
		r = ++tot, key(r) = k, pri(r) = rand();
		cnt(r) = size(r) = 1, lc(r) = rc(r) = 0;
		return;
	} else ++size(r);
	if (k == key(r)) ++cnt(r);
	else if (k < key(r)) {
		insert(lc(r), k);
		if (pri(lc(r)) < pri(r)) zig(r);
	} else {
		insert(rc(r), k);
		if (pri(rc(r)) < pri(r)) zag(r);
	}
}

void del(int &r, int k) {
	if (key(r) == k) {
		if (cnt(r) >= 2) --cnt(r), --size(r);
		else if(!lc(r) || !rc(r)) r = lc(r) + rc(r);
		else if(pri(lc(r)) < pri(rc(r))) zig(r), del(r, k);
		else zag(r), del(r, k);
		return;
	} 
	--size(r);
	if (k < key(r)) del(lc(r), k);
	else del(rc(r), k);
}

int queryPre(int k) {
	int r = rt, res = inf;
	while (r) {
		if (key(r) <= k) res = key(r), r = rc(r);
		else r = lc(r);
	}
	return res;
}
int queryNxt(int k) {
	int r = rt, res = inf;
	while (r) {
		if (k < key(r)) res = key(r), r = lc(r);
		else r = rc(r);
	}
	return res;
}

int queryKth(int k) {
	int r = rt, res = inf;
	while (r) {
		if (size(lc(r)) < k && size(lc(r)) + cnt(r) >= k) return key(r);
		else if(size(lc(r)) >= k) r = lc(r); 
		else k -= size(lc(r)) + cnt(r), r = rc(r);
	}
	return res;
}

int queryRand(int k) {
	int r = rt, res = 0;
	while (r) {
		if (k == key(r)) return size(lc(r)) + cnt(r) + 1;
		else if (k < key(r)) r = lc(r); 
		else res += size(lc(r)) + cnt(r), r = rc(r);   
	}
	return res;
}
void show(int x) {
	printf("%d %d %d %d
", lc(x), rc(x), key(x), pri(x));
	if (lc(x) != 0) show(lc(x));
	if (rc(x) != 0) show(rc(x));
}
int main() {
	n = read();
	srand(time(NULL));
	// write(n), putchar('
');
	for (int i = 1, a, b, p, q, j; i <= n; ++i) {
		a = read(), b =read();
		// printf("%d %d
", a, b);
		if (a == 0) {
			if (flag) insert(rt, b);
			else {
				if (!flag && rt == 0) insert(rt, b), flag = true;
				else {
					j = inf;
					p = queryPre(b), q = queryNxt(b);
					if (p != inf) j = b - p;
					if (q != inf && q - b < j) j = q - b;
					if (j != inf) ans = ((long long)ans + j % mod) % mod;
					if (p != inf && j == b - p) del(rt, p); 
					else if(q != inf && j == q - b) del(rt, q);
				}
			} 
		} else if (a == 1) {
			if (!flag) insert(rt, b);
			else {
				if (flag && rt == 0) insert(rt, b), flag = false;
				else {
					j = inf;
					p = queryPre(b), q = queryNxt(b);
					if (p != inf) j = b - p;
					if (q != inf && q - b < j) j = q - b;
					if (j != inf) ans = ((long long)ans + j % mod) % mod;
					if (p != inf && j == b - p) del(rt, p); 
					else if(q != inf && j == q - b) del(rt, q);
				}
			}
		}
	}
	write(ans);
	return 0;
}