luogu2698 [USACO12MAR]花盆Flowerpot

单调队列+二分答案

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
struct Node{
	int x, y;
}nd[100005];
int n, d, ans, q1[100005], q2[100005], l1, r1, l2, r2;
bool cmp(Node u, Node v){
	return u.x<v.x;
}
bool check(int lim){
	l1 = 1, r1 = 0;
	l2 = 1, r2 = 0;
	for(int i=1; i<=n; i++){
		while(l1<=r1 && nd[q1[l1]].x<nd[i].x-lim)	l1++;
		while(l1<=r1 && nd[q1[r1]].y>nd[i].y)	r1--;
		q1[++r1] = i;
		while(l2<=r2 && nd[q2[l2]].x<nd[i].x-lim)	l2++;
		while(l2<=r2 && nd[q2[r2]].y<nd[i].y)	r2--;
		q2[++r2] = i;
		if(nd[q2[l2]].y-nd[q1[l1]].y>=d)	return true;
	}
	return false;
}
int main(){
	cin>>n>>d;
	for(int i=1; i<=n; i++)
		scanf("%d %d", &nd[i].x, &nd[i].y);
	sort(nd+1, nd+1+n, cmp);
	int l=0, r=nd[n].x-nd[1].x, mid;
	while(l<=r){
		mid = (l + r) >> 1;
		if(check(mid)){
			ans = mid;
			r = mid - 1;
		}
		else	l = mid + 1;
	}
	if(ans==0)	cout<<"-1"<<endl;
	else	cout<<ans<<endl;
	return 0;
}