CodeForces

CodeForces - 1201B
首先和是偶数，最大的数要小于总和的一半

#include <iostream>
#include <cstdio>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstring>
#define inf 2147483647
#define N 1000010
#define p(a) putchar(a)
#define For(i,a,b) for(long long i=a;i<=b;++i)
//by war
//2020.2.10
using namespace std;
long long n,ans;
long long a[N];
void in(long long &x){
    long long y=1;char c=getchar();x=0;
    while(c<'0'||c>'9'){if(c=='-')y=-1;c=getchar();}
    while(c<='9'&&c>='0'){ x=(x<<1)+(x<<3)+c-'0';c=getchar();}
    x*=y;
}
void o(long long x){
    if(x<0){p('-');x=-x;}
    if(x>9)o(x/10);
    p(x%10+'0');
}

signed main(){
    in(n);
    For(i,1,n){
        in(a[i]);
        ans+=a[i];
    }
    sort(a+1,a+n+1);
    if(ans%2==0&&a[n]<=ans/2) puts("YES");
    else puts("NO");
    return 0;
}