Binary Search

easycodingAlgorithmsBinary SearchArrays~15 min

Asked at Google, Meta

Overview

Given a sorted (ascending) array of integers nums and a target value target, return the index of target if found. Otherwise return -1.

Constraints

1 <= nums.length <= 10,000
All values in nums are unique and sorted in ascending order.
-10,000 <= nums[i], target <= 10,000
Must run in O(log n) time.

Examples

search([-1, 0, 3, 5, 9, 12], 9);
// => 4

search([-1, 0, 3, 5, 9, 12], 2);
// => -1

Solution

Reveal solution

function search(nums, target) {
  let lo = 0, hi = nums.length - 1;
  while (lo <= hi) {
    const mid = (lo + hi) >> 1;
    if (nums[mid] === target) return mid;
    if (nums[mid] < target) lo = mid + 1;
    else hi = mid - 1;
  }
  return -1;
}

Resources

binary-search.js

Binary Search

easycodingAlgorithmsBinary Search

Overview

Given a sorted (ascending) array of integers nums and a target value target, return the index of target if found. Otherwise return -1.

Constraints

1 <= nums.length <= 10,000
All values in nums are unique and sorted in ascending order.
-10,000 <= nums[i], target <= 10,000
Must run in O(log n) time.

Examples

search([-1, 0, 3, 5, 9, 12], 9);
// => 4

search([-1, 0, 3, 5, 9, 12], 2);
// => -1

Solution

Reveal solution

function search(nums, target) {
  let lo = 0, hi = nums.length - 1;
  while (lo <= hi) {
    const mid = (lo + hi) >> 1;
    if (nums[mid] === target) return mid;
    if (nums[mid] < target) lo = mid + 1;
    else hi = mid - 1;
  }
  return -1;
}

Resources

NameTopicDifficulty

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