0704-binary-search.rb

# frozen_string_literal: true

# 704. Binary Search
# https://leetcode.com/problems/binary-search

=begin

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.

=end

# Runtime: 100 ms
# Memory: 213.7 MB
# @param {Integer[]} nums
# @param {Integer} target
# @return {Integer}
def search(nums, target)
  nums.bsearch_index { |i| target - i } || -1
end

# **************** #
#       TEST       #
# **************** #

require "test/unit"
class Test_search < Test::Unit::TestCase
  def test_
    assert_equal 4, search([-1, 0, 3, 5, 9, 12], 9)
    assert_equal(-1, search([-1, 0, 3, 5, 9, 12], 2))
  end
end