m1509 v3.c

int cmp(const void* one, const void* two) {
    return *((int *) one) - *((int *) two);
}

int minDifference(int* nums, int numsSize) {
    if (numsSize <= 4) 
        return 0;

    int top4[4] = {nums[0], nums[1], nums[2], nums[3]};
    qsort(top4, 4, sizeof(int), cmp);
    int bot4[4] = {top4[3], top4[2], top4[1], top4[0]};

    for (int i = 4; i < numsSize; i++) {
        if (nums[i] > top4[3]) {
            top4[0] = top4[1];
            top4[1] = top4[2];
            top4[2] = top4[3];
            top4[3] = nums[i];
        } else if (nums[i] > top4[2]) {
            top4[0] = top4[1];
            top4[1] = top4[2];
            top4[2] = nums[i];
        } else if (nums[i] > top4[1]) {
            top4[0] = top4[1];
            top4[1] = nums[i];
        } else if (nums[i] > top4[0]) {
            top4[0] = nums[i];
        }

        if (nums[i] < bot4[3]) {
            bot4[0] = bot4[1];
            bot4[1] = bot4[2];
            bot4[2] = bot4[3];
            bot4[3] = nums[i];
        } else if (nums[i] < bot4[2]) {
            bot4[0] = bot4[1];
            bot4[1] = bot4[2];
            bot4[2] = nums[i];
        } else if (nums[i] < bot4[1]) {
            bot4[0] = bot4[1];
            bot4[1] = nums[i];
        } else if (nums[i] < bot4[0]) {
            bot4[0] = nums[i];
        }
    }

    int a = (top4[3] - bot4[0] < top4[2] - bot4[1]) ? top4[3] - bot4[0] : top4[2] - bot4[1];
    int b = (top4[1] - bot4[2] < top4[0] - bot4[3]) ? top4[1] - bot4[2] : top4[0] - bot4[3];
    return (a < b) ? a : b;

}