AtCoder Regular Contest 080 C - 4-adjacent

地址：http://arc080.contest.atcoder.jp/tasks/arc080_a

题目：

C - 4-adjacent

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Time limit : 2sec / Memory limit : 256MB

Score : 400 points

Problem Statement

We have a sequence of length N, a=(a1,a2,…,aN). Each ai is a positive integer.

Snuke's objective is to permute the element in a so that the following condition is satisfied:

• For each 1≤i≤N−1, the product of ai and ai+1 is a multiple of 4.

Determine whether Snuke can achieve his objective.

Constraints

• 2≤N≤105
• ai is an integer.
• 1≤ai≤109

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Input

Input is given from Standard Input in the following format:

N
a1 a2 … aN

Output

If Snuke can achieve his objective, print Yes; otherwise, print No.

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思路：求膜2为1，膜4为0的数有多少个就好了。

 #include <bits/stdc++.h>

 using namespace std;

 #define MP make_pair
 #define PB push_back
 typedef long long LL;
 typedef pair<int,int> PII;
 const double eps=1e-;
 const double pi=acos(-1.0);
 const int K=1e6+;
 const int mod=1e9+;

 int n,a,b,c,ans;

 int main(void)
 {
     scanf("%d",&n);
     for(int i=,x;i<=n;i++)
     {
         scanf("%d",&x);
         if(x%==) c++;
         else if(x%==) b++;
         else a++;
     }
     c-=a;
     if(c>=||(c==-&&b==)) puts("Yes");
     else    puts("No");
     return ;
 }