Maximum sum

Description

Given a set of n integers: A={a1, a2,…, an}, we define a function d(A) as below:

Your task is to calculate d(A).

Input

The input consists of T(<=30) test cases. The number of test cases (T) is given in the first line of the input.
Each test case contains two lines. The first line is an integer n(2<=n<=50000). The second line contains n integers: a1, a2, …, an. (|ai| <= 10000).There is an empty line after each case.

Output

Print exactly one line for each test case. The line should contain the integer d(A).

Sample Input

1
10
1 -1 2 2 3 -3 4 -4 5 -5

Sample Output

13

Hint

In the sample, we choose {2,2,3,-3,4} and {5}, then we can get the answer.

Huge input,scanf is recommended.

code

#include <stdio.h>
#include <iostream>
using namespace std; 
int a[50005], m[50005];
const int MIN = -999999999; 
int main()
{
    int c;
    int n;
    int i;
    int temp, sum, ans;
    scanf("%d", &c);
    while(c--)
    {
        scanf("%d", &n);
        temp = MIN;
        sum = 0;
        for(i = 1; i <= n; i++)
        {
            scanf("%d", &a[i]);
            sum += a[i];
            if(sum > temp) temp = sum;
            m[i] = temp;  // 记录每个字段的最大值。
            if(sum < 0) sum = 0;
        }
        sum = 0;
        temp = MIN;
        ans = MIN;
        for(i = n; i > 1; i--)
        {
            sum += a[i];
            if(sum > temp) temp = sum;
            ans = max(ans, temp + m[i-1]);
            if(sum < 0) sum = 0;
        }
        printf("%d\n", ans);
    }
    return 0;
}