BZOJ 2091: [Poi2010]The Minima Game

/**************************************************************
    Problem: 2091
    User: BeiYu
    Language: C++
    Result: Accepted
    Time:1248 ms
    Memory:16916 kb
****************************************************************/
 
#include <bits/stdc++.h>
using namespace std;
 
typedef long long LL;
const int N = 1e6+50;
 
LL n,mx;
LL a[N],f[N];
 
inline LL in(LL x=0,char ch=getchar()) { while(ch>‘9‘ || ch<‘0‘) ch=getchar();
    while(ch>=‘0‘ && ch<=‘9‘) x=x*10+ch-‘0‘,ch=getchar();return x; }
int main() {
    n=in();
    for(int i=1;i<=n;i++) a[i]=in();
    sort(a+1,a+n+1);mx=a[1];
    for(int i=1;i<=n;i++) f[i]=mx,mx=max(mx,a[i+1]-f[i]);
    cout<<f[n]<<endl;
    return 0;
}