【BZOJ3314】 [Usaco2013 Nov]Crowded Cows 单调队列

第一次写单调队列太垃圾。。。

左右各扫一遍即可。

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <algorithm>
 5 #define N 50010
 6 using namespace std;
 7 struct data
 8 {
 9     int x,h;
10 }a[N],q[N];
11 int n,m,l,r;
12 int ok1[N],ok2[N];
13 inline int read()
14 {
15     int f=1,ans=0;
16     char c;
17     while (!isdigit(c=getchar())) if (c=='-') f=-1;
18     ans=c-'0';
19     while (isdigit(c=getchar())) ans=ans*10+c-'0';
20     return ans*f;
21 }
22 bool cmp(data a,data b) {return a.x<b.x;}
23 int main()
24 {
25     n=read(); m=read();
26     for (int i=1;i<=n;i++) a[i].x=read(),a[i].h=read();
27     sort(a+1,a+n+1,cmp);
28     l=1; r=0;
29     for (int i=1;i<=n;i++)
30     {
31         while (l<=r && q[r].h<a[i].h) r--;
32         q[++r]=a[i];
33         while (l<=r && q[l].x<a[i].x-m) l++;
34         if (q[l].h>=2*a[i].h) ok1[i]=1;
35     }
36     l=1; r=0;
37     for (int i=n;i>=1;i--)
38     {
39         while (l<=r && q[r].h<a[i].h) r--;
40         q[++r]=a[i];
41         while (l<=r && q[l].x>a[i].x+m) l++;
42         if (q[l].h>=2*a[i].h) ok2[i]=1;
43     }
44     int ans=0;
45     for (int i=1;i<=n;i++)
46         if (ok1[i]&&ok2[i]) ans++;
47     printf("%d\n",ans);
48     return 0;
49 }

View Code

Description

Farmer John's N cows (1 <= N <= 50,000) are grazing along a one-dimensional fence. Cow i is standing at location x(i) and has height h(i) (1 <= x(i),h(i) <= 1,000,000,000). A cow feels "crowded" if there is another cow at least twice her height within distance D on her left, and also another cow at least twice her height within distance D on her right (1 <= D <= 1,000,000,000). Since crowded cows produce less milk, Farmer John would like to count the number of such cows. Please help him.

N头牛在一个坐标轴上，每头牛有个高度。现给出一个距离值D。

如果某头牛在它的左边，在距离D的范围内，如果找到某个牛的高度至少是它的两倍，且在右边也能找到这样的牛的话。则此牛会感觉到不舒服。

问有多少头会感到不舒服。

Input

* Line 1: Two integers, N and D.

* Lines 2..1+N: Line i+1 contains the integers x(i) and h(i). The locations of all N cows are distinct.

Output

* Line 1: The number of crowded cows.

Sample Input

6 4
10 3
6 2
5 3
9 7
3 6
11 2

INPUT DETAILS: There are 6 cows, with a distance threshold of 4 for feeling crowded. Cow #1 lives at position x=10 and has height h=3, and so on.

Sample Output

2
OUTPUT DETAILS: The cows at positions x=5 and x=6 are both crowded.

HINT

Source

Silver

转载于:https://www.cnblogs.com/DMoon/p/5422650.html