C/C++ :: Running Array In Less Complexity

Giving a dynamic array, we want to pass the array elements from a file. The first number in the file N gives us the array length. They follow N numbers, the actual elements of the array.

Three brothers are going to work in the shop of their father for a time. The shop is doing well and every day generates profit which the three brothers may provide. The brothers agreed that they would divide the total time in three successive parts, not necessarily equal duration, and that each one will be working in the shop during one of these parts and collects the corresponding profit on his behalf. But they want to make a deal fairly, so that one received from three more profit someone else. Specifically, they want to minimize the profit the most favored of the three will receive.

I first created a program that WORKS! with complexity O(n3).

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
int sum_array(int* array, int cnt){
int res = 0;
int i;
for ( i = 0; i < cnt ; ++i)

[Code] .....

Let's assume that we have the following input:

10

1 1 8 1 1 3 4 9 5 2

The ouptut should be 15 -> A = 1 + 1 + 8 + 1 + 1 + 3 = 15 , B = 4 + 9 = 13 , C = 5 + 2 = 7.

But the ouptut is 16!

How can I reduce the complexity of my first working! C code?