CF1268B Domino for Young 黑白染色

这个黑白染色的思路真的是很巧妙啊

code: 

#include <cstdio>  
#include <string>
#include <algorithm> 
#define ll long long 
using namespace std;  
namespace IO {  
    void setIO(string s) 
    {
        string in=s+".in"; 
        freopen(in.c_str(),"r",stdin); 
    }
};  
ll ans[2];   
int main() 
{ 
    // IO::setIO("input");  
    int i,j,n,x; 
    scanf("%d",&n); 
    for(i=1;i<=n;++i)   
    {
        scanf("%d",&x); 
        ans[i%2]+=x/2;    
        ans[(i+1)%2]+=x-x/2;      
    } 
    printf("%lld\n",min(ans[0],ans[1]));   
    return 0; 
}