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Leetcode167-Two Sum II-Input Array Is Sorted

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Solution Report of LeetCode Acceptted

Description

Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2.

Note:

  • Your returned answers (both index1 and index2) are not zero-based.
  • You may assume that each input would have exactly one solution and you may not use the same element twice.

Example

Example 1:

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Input: numbers = [2,7,11,15], target = 9
Output: [1,2]
Explanation: The sum of 2 and 7 is 9. Therefore index1 = 1, index2 = 2.

Example 2:
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Input: numbers = [2,3,4], target = 6
Output: [1,3]

Example 3:
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Input: numbers = [-1,0], target = -1
Output: [1,2]

Constraints:

  • 2 <= nums.length <= 3 * 104
  • -1000 <= nums[i] <= 1000
  • nums is sorted in increasing order.

  • -1000 <= target <= 1000

    Solution

  • Time Complexity:

  • Space Complexity: 
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class Solution {
    public int[] twoSum(int[] numbers, int target) {
        int i = 0;
        int j = numbers.length - 1;
        while(i < j){
            int cur = numbers[i] + numbers[j];
            if (cur == target){
                break;
            }
            else if (cur < target){
                i++;
            }
            else j--;
        }
        return new int[]{i + 1, j + 1};
    }
}