binary-search.js

/**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) {
  if (nums.length === 0) {
    return -1;
  }

  let left = 0;
  let right = nums.length - 1;

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