Submission #845059

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Source Code Expand

#include <bits/stdc++.h>

#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)

#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=int(a)-1;i>=int(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)

#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
#define popcount(n) (__builtin_popcountll(n))

template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}

using namespace std;
using ll=long long;
ll a[100010];

int main(void){
	int n;
	cin >> n;
	rep(i,n) cin >> a[i];

	ll ans=0LL;

	if(n==1){
		cout << a[0]/2LL << endl;
		return 0;
	}

	rep(i,1,n){
		ll sum=(a[i]+a[i-1]);
		ll cnt=sum/2LL;
		ans+=cnt;

		if(sum%2==1){
			if(a[i]==0)
				a[i-1]=1LL;
			else
				a[i]=1LL;
		}else
			a[i-1]=a[i]=0LL;
	}	

	cout << ans << endl;
	return 0;
}

Submission Info

Judge Result