POJ_2479

Maximum sum

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 37754 Accepted: 11797

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

1101 -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.

#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;
}