0704-binary-search.js

/**
 * 704. Binary Search
 * https://leetcode.com/problems/binary-search/
 * Difficulty: Easy
 *
 * 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.
 */

/**
 * @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 pivot = Math.floor((right + left) / 2);
    if (nums[pivot] === target) return pivot;
    if (target < nums[pivot]) right = pivot - 1;
    else left = pivot + 1;
  }

  return -1;
};

// var search = function(nums, target) {
//   l = 0
//   r = nums.length

//   while (l <= r) {
//       pivot = Math.floor((l + r) / 2)
//       if (nums[pivot] === target) return pivot
//       if (target < nums[pivot]) r = pivot - 1
//       else l = pivot + 1
//   }

//   return - 1
// };