Splitting Pile --AtCoder

题目描述

Snuke and Raccoon have a heap of N cards. The i-th card from the top has the integer ai written on it.
They will share these cards. First, Snuke will take some number of cards from the top of the heap, then Raccoon will take all the remaining cards. Here, both Snuke and Raccoon have to take at least one card.
Let the sum of the integers on Snuke's cards and Raccoon's cards be x and y, respectively. They would like to minimize |x−y|. Find the minimum possible value of |x−y|.

Constraints
2≤N≤2×105
−109≤ai≤109
ai is an integer.

输入

Input is given from Standard Input in the following format:
N
a1 a2 … aN

输出

Print the answer.

样例输入

6
1 2 3 4 5 6

样例输出

1

#include <iostream>
#include <string>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
#define range(i,a,b) for(int i=a;i<=b;++i)
#define LL long long
#define rerange(i,a,b) for(int i=a;i>=b;--i)
#define fill(arr,tmp) memset(arr,tmp,sizeof(arr))
using namespace std;
const int mxn=2e5+5;
LL n,num[mxn],sum[mxn],SUM;
void init(){
    cin>>n;
    range(i,1,n){
        cin>>num[i];
        sum[i]=sum[i-1]+num[i];
        SUM+=num[i];
    }
}
void solve(){
    LL MIN=0x7f7f7f7f;
    range(i,1,n-1)if(MIN>abs((sum[i]<<1)-SUM))MIN=abs((sum[i]<<1)-SUM);
    cout<<MIN<<endl;
}
int main() {
    init();
    solve();
    return 0;
}