content: package LeetCode.Easy.TwoSum_II;
  
  // import java.util.HashMap;
  
  /*
    167. Two Sum II - Input array is sorted
  
    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 1:
    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:
    Input: numbers = [2,3,4], target = 6
    Output: [1,3]
  
    Example 3:
    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
  */
  
  public class Solution {
    public int[] twoSum(int[] numbers, int target) {
      if (numbers == null || numbers.length == 0) return new int[0];
  
      /**
       * * HashMap approach
       */
      // HashMap<Integer, Integer> map = new HashMap<>();
  
      // for (int i=0; i<numbers.length; i++)
      //   if (map.containsKey(target - numbers[i]))
      //     return new int[] {map.get(target - numbers[i]), i + 1};
      //   else
      //     map.put(numbers[i], i + 1);
  
      /**
       * * Since the array is already
       * * sorted, so we can use binary
       * * search to check
       */
      int i = 0, j = numbers.length - 1;
      while (i < j) {
        if (numbers[i] + numbers[j] == target) return new int[] {i + 1, j + 1};
        else if (numbers[i] + numbers[j] > target) --j;
        else ++i;
      }
  
      return new int[0];
    }
  
    public static void main(String[] args) {
      Solution solution = new Solution();
  
      int[] res = solution.twoSum(new int[] {2, 7, 11, 15}, 9);
  
      for (int n : res) System.out.print(n + " ");
    }
  }
  