class Solution(object):
    # 1. two pointer 구현. hash table 사용하면 공간 복잡도 O(n)이라서 이렇게 함.
    # Time complexity : O(n)
    # Space complexity : O(1)
    def twoSum(self, numbers, target):
        """
        :type numbers: List[int]
        :type target: int
        :rtype: List[int]
        """
        idx1, idx2 = 0, len(numbers)-1
        while idx1 < idx2:
            cur_sum = numbers[idx1] + numbers[idx2]
            # print(idx1, idx2, cur_sum)
            if cur_sum == target:
                return [idx1+1, idx2+1]
            elif cur_sum > target:
                idx2 -= 1
            else:
                idx1 += 1