Closest In Sorted Array

Given a target integer T and an integer array A sorted in ascending order, find the index i in A such that A[i] is closest to T.

Assumptions

• There can be duplicate elements in the array, and we can return any of the indices with same value.

Examples

• A = {1, 2, 3}, T = 2, return 1
• A = {1, 4, 6}, T = 3, return 1
• A = {1, 4, 6}, T = 5, return 1 or 2
• A = {1, 3, 3, 4}, T = 2, return 0 or 1 or 2

Corner Cases

• What if A is null or A is of zero length? We should return -1 in this case.

time: O(log(n)), space: O(1)

public class Solution {
  public int closest(int[] array, int target) {
    // Write your solution here
    if(array == null || array.length == 0) return -1;
    int left = 0, right = array.length - 1;
    while(left + 1 < right) {
      int mid = left + (right - left) / 2;
      if(array[mid] == target)
        return mid;
      else if(array[mid] < target)
        left = mid;
      else
        right = mid;
    }
    return Math.abs(array[left] - target) < Math.abs(array[right] - target) ? left : right;
  }
}