001_TwoSum.c

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
int* twoSum(int* nums, int numsSize, int target) {
	int i, j, key;
	int* res = (int *)malloc(2 * sizeof(int));
	int* tmp = (int *)malloc(numsSize * sizeof(int));

	for(i = 0; i < numsSize; i++) {
		*(tmp + i) = *(nums + i);
	}

	// Sorting tmp[] by using Insertion Sort.
	for(j = 1; j < numsSize; j++) {
		key = *(tmp +j);
		i = j - 1;

		while(i >=0 && *(tmp + i) > key) {
			*(tmp + i + 1) = *(tmp + i);
			i--;
		}
		*(tmp + i + 1) = key;
	}

	for(i = numsSize - 1; i > 0; i--) {
		if(*(tmp + i) * 2 < target) {
			break;
		}

		for(j = 0; j < i; j++) {
			if(*(tmp + i) + *(tmp + j) > target) {
				break;
			}

			if(*(tmp + i) + *(tmp + j) == target) {
				int m = 0;
				int n = 0;

				for(m = 0; m < numsSize; m++) {
					if((*(tmp + i) == *(nums + m)) || (*(tmp + j) == *(nums + m))) {
						if(n == 0) {
							*res = m;
							n++;
						}
						else {
							*(res + 1) = m;
						}
					}
				}
				free(tmp);
				tmp = NULL;

				return res;
			}
		}
	}

	*res = 0;
	*(res + 1) = 0;
	free(tmp);
	tmp = NULL;

	return res;
}