【贪心】Codeforces Round #407 (Div. 2) A. Anastasia and pebbles

贪心地一个一个尽可能往口袋里放，容易发现和顺序无关。

#include<cstdio>
#include<iostream>
using namespace std;
typedef long long ll;
int n,m,a[100100];
ll ans;
int main(){
//	freopen("a.in","r",stdin);
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;++i){
		scanf("%d",&a[i]);
	}
	int i=1;
	while(i<=n){
		if(a[i]<=m && a[i+1]<=m){
			i+=2;
			++ans;
		}
		else if(a[i]<=m && a[i+1]>m){
			a[i+1]-=m;
			++i;
			++ans;
		}
		else if(a[i]<2*m){
			++i;
			++ans;
		}
		else if(a[i]>=2*m){
			ans+=(ll)(a[i]/(2*m));
			a[i]%=(2*m);
			if(a[i]==0){
				++i;
			}
		}
	}
	cout<<ans<<endl;
	return 0;
}