binary-search.py

'''

Gven 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].


'''


class Solution:
    def search(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        # Approach one
        # l,r = 0 , len(nums)-1
        # while l <= r:
        #     mid = (l + r) // 2
        #     if nums[mid] == target: return mid
        #     if l == r : break
        #     if nums[mid] < target:
        #         l = mid + 1
        #     else :
        #         r = mid
        # return -1

        # Approach one
        l,r = 0 , len(nums)-1
        while l <= r:
            mid = (l + r) // 2
            if nums[mid] == target: return mid
            if nums[mid] < target:
                l = mid + 1
            else :
                r = mid - 1
        return -1