704. Binary Search

Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If target exists, then return its index, otherwise return -1.

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

Note:

You may assume that all elements in nums are unique.
n will be in the range [1, 10000].
The value of each element in nums will be in the range [-9999, 9999].

Source

Code

In [1]:

def binary_search(nums, target):
    pass

Check

In [3]:

nums = [-1,0,3,5,9,12]
target = 9
binary_search(nums, target)

Out[3]:

In [4]:

nums = [-1,0,3,5,9,12]
target = 2
binary_search(nums, target)

Out[4]:

-1

Follow up:

Solve it both iteratively and recursively. Solve it using built-in methods too.

In [5]:

def binary_search(nums, target):
    pass