cf C. Counting Kangaroos is Fun
http://codeforces.com/contest/373/problem/C
贪心,先排序,然后从n/2位置倒着找每一个可不可以放到别的袋鼠内。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 #define maxn 5000001 5 using namespace std; 6 7 int a[maxn]; 8 bool vis[maxn]; 9 int n; 10 11 int main() 12 { 13 while(scanf("%d",&n)!=EOF) 14 { 15 memset(vis,false,sizeof(vis)); 16 for(int i=0; i<n; i++) 17 { 18 scanf("%d",&a[i]); 19 } 20 sort(a,a+n); 21 int j=n-1; 22 int ans=0; 23 for(int i=n/2-1; i>=0; i--) 24 { 25 if(a[j]>=2*a[i]) 26 { 27 j--; 28 ans++; 29 } 30 } 31 printf("%d\n",n-ans); 32 } 33 return 0; 34 }