704_binary_search.py

'''
704. Binary Search
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.



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


Constraints:

1 <= nums.length <= 104
-104 < nums[i], target < 104
All the integers in nums are unique.
nums is sorted in ascending order.
'''


class Solution(object):
    def search(self, nums, target):
        left, right = 0, len(nums)-1
        while (left <= right):
            mid = left + (right - left)//2
            if nums[mid] == target:
                return mid
            elif nums[mid] < target:
                left = mid +1
            else:
                right = mid -1
        return -1

        # # two point


if __name__ == '__main__':
    s = Solution()
    print(s.search([-1,0,3,5,9,12], 9))