636 Smallest Element Larger than Target (Lai)

Given a target integer T and an integer array A sorted in ascending order, find the index of the smallest element in A that is larger than T or return -1 if there is no such index.

Assumptions

There can be duplicate elements in the array.

Examples

A = {1, 2, 3}, T = 1, return 1

A = {1, 2, 3}, T = 3, return -1

A = {1, 2, 2, 2, 3}, T = 1, return 1

Corner Cases

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

Solution:

public class Solution {
  public int smallestElementLargerThanTarget(int[] array, int target) {
    // Write your solution here
    if (array == null || array.length == 0){
      return -1;
    }

    int left = 0; 
    int right = array.length -1;

    while(left <= right){
      int mid = left + (right - left)/2;
      if (array[mid] <= target){
        left = mid + 1;
      }else {
        right = mid - 1;
      }
    }

    if (left == array.length){
      return -1;
    }else{
      return left;
    }
  }
}
// TC: O(logn)
// SC: O(1)