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class Solution {
    public int[] twoSum(int[] nums, int target) {
        int left = 0, right = nums.length - 1;
        while (left < right) {
            if (nums[left] + nums[right] == target) {
                return new int[] { left + 1, right + 1 };
            } else if (nums[left] + nums[right] < target) {
                left += 1;
            } else {
                right -= 1;
            }
        }
        return new int[0];
    }
}

two pointers. 没什么好说的.

时间复杂度: O(n)
空间复杂度: O(1)