返回整数数组最大子数组的和

#include <stdio.h>

typedef struct index {
    int left;
    int right;
    int sum;
} index_t;

index_t find_max_crossing_subarray(int* a, int low, int mid, int high)
{
    int left_sum = 0x80000000;
    int right_sum = 0x80000000;
    int sum = 0;
    int max_left, max_right;

    int i;

    index_t value;

    for (i = mid; i >= low; i--) {
        sum += a[i];
        if (sum > left_sum) {
            left_sum = sum;
            max_left = i;
        }
    }

    sum = 0;
    for (i = mid + 1; i <= high; i++) {
        sum += a[i];
        if (sum > right_sum) {
            right_sum = sum;
            max_right = i;
        }
    }

    value.left = max_left;
    value.right = max_right;
    value.sum = left_sum + right_sum;

    return value;
}

index_t find_maximum_subarray(int *a, int low, int high)
{
    index_t left_value, right_value, value;
    int mid;

    if (high == low) {
        value.left = low;
        value.right = high;
        value.sum = a[low];
        return value;
    } else {
        mid = (high + low)/2;
        left_value = find_maximum_subarray(a, low, mid);
        right_value = find_maximum_subarray(a, mid + 1, high);
        value = find_max_crossing_subarray(a, low, mid, high);

        if (left_value.sum >= right_value.sum && left_value.sum >= value.sum)
            return left_value;
        else if (right_value.sum >= left_value.sum && right_value.sum >= value.sum)
            return right_value;
        else
            return value;
    }
}

int main()
{
    int i,x;
    printf("输入数组元素个数");
    scanf("%d",&x);
    printf("输入数组元素\n");
    int a[x];
    for(i=0;i<x;i++)
    {
        scanf("%d",&a[i]);
    }

    index_t value;

    value = find_maximum_subarray(a, 0, x-1);

    printf("The maximum subarray is from %d to %d, sum is %d\n", value.left, value.right, value.sum);

    return 0;
}

结果：