codeforces 373 C. Counting Kangaroos is Fun

2016-02-18 · 1 min read · greedy

http://codeforces.com/contest/373/problem/C 题意：n个袋鼠，每个袋鼠的size为a[i],一只袋鼠的size至少是另一只两倍时才能将它装下，被装下的袋鼠不能再装别的袋鼠且不能被看见。问能看见的袋鼠最少是多少。思路：贪心。最多有n/2个袋鼠被装下。先排序，然后贪心即可。

/* ***********************************************
Author :111qqz
Created Time :2016年02月18日 星期四 14时32分29秒
File Name :code/cf/problem/373C.cpp
************************************************ */

 1#include <cstdio>
 2#include <cstring>
 3#include <iostream>
 4#include <algorithm>
 5#include <vector>
 6#include <queue>
 7#include <set>
 8#include <map>
 9#include <string>
10#include <cmath>
11#include <cstdlib>
12#include <ctime>
13#define fst first
14#define sec second
15#define lson l,m,rt<<1
16#define rson m+1,r,rt<<1|1
17#define ms(a,x) memset(a,x,sizeof(a))
18typedef long long LL;
19#define pi pair < int ,int >
20#define MP make_pair

 1using namespace std;
 2const double eps = 1E-8;
 3const int dx4[4]={1,0,0,-1};
 4const int dy4[4]={0,-1,1,0};
 5const int inf = 0x3f3f3f3f;
 6const int N=5E5+7;
 7int a[N];
 8int n;
 9int main()
10{
11	#ifndef  ONLINE_JUDGE 
12	freopen("code/in.txt","r",stdin);
13  #endif
14	cin>>n;
15	for ( int i = 1 ; i <= n ; i++) scanf("%d",&a[i]);

	sort(a+1,a+n+1);

 1	int j = n;
 2	int ans = 0 ;
 3	for (int  i = n/2 ;  i >=1 ; i--)
 4	{
 5	    if (a[j]>=2*a[i])
 6	    {
 7		ans++;
 8		j--;
 9	    }
10	}
11	cout<<n-ans<<endl;

1  #ifndef ONLINE_JUDGE  
2  fclose(stdin);
3  #endif
4    return 0;
5}