【BZOJ3314】 [Usaco2013 Nov]Crowded Cows 单调队列
第一次写单调队列太垃圾。。。
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 }
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
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
OUTPUT DETAILS: The cows at positions x=5 and x=6 are both crowded.
