leetcode/work/Easy/Array/704.binary-search.js

/*
 * 704. Binary Search
 * Difficulty: Easy
 * https://leetcode.com/problems/binary-search/
 * 
 * ──────────────────────────────────────────────────
 * 
 * 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 <= 10^4
 * 
 * 	• -10^4 < nums[i], target < 10^4
 * 
 * 	• All the integers in nums are unique.
 * 
 * 	• nums is sorted in ascending order.
*/

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number}
 */
var search = function(nums, target) {
    let left = 0;
    let right = nums.length - 1;

    while(left <= right) {
        const mid = left + Math.floor((right - left) / 2);
        if (nums[mid] === target) {
            return mid;
        } else if(nums[mid] < target){
            left = mid + 1;
        } else if (nums[mid] > target) {
            right = mid - 1;
        }
    }
    return -1;
};