704. Binary Search #

Problem Statement: #

Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.

You must write an algorithm with O(log n) runtime complexity.

Example 1: #

Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4

Example 2: #

Input: nums = [-1,0,3,5,9,12], target = 2
Output: -1
Explanation: 2 does not exist in nums so return -1

Constraints: #

• 1 <= nums.length <= 10⁴
• -10⁴ < nums[i], target < 10⁴
• All the integers in nums are unique.
• nums is sorted in ascending order.

Solution: #

public int search(int[] nums, int target) {
  int low = 0,
      mid = 0,
      high = nums.length - 1;
  while (low <= high) {
    mid = low + (high - low) / 2;
    if (nums[mid] == target)
      return mid;
    else if (nums[mid] < target)
      low = mid + 1;
    else
      high = mid - 1;
  }
  return -1;
}

... #