Add solution for neetcode: binary search

neetcode/arrays/binary_search/README.md

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+Binary Search
+You are given an array of distinct integers nums, sorted in ascending order, and an integer target.
+
+Implement a function to search for target within nums. If it exists, then return its index, otherwise, return -1.
+
+Your solution must run in O(logn) time.
+
+Example 1:
+
+Input: nums = [-1,0,2,4,6,8], target = 4
+
+Output: 3
+Example 2:
+
+Input: nums = [-1,0,2,4,6,8], target = 3
+
+Output: -1
+Constraints:
+
+1 <= nums.length <= 10000.
+-10000 < nums[i], target < 10000

neetcode/arrays/binary_search/solution.py

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+from typing import List
+
+
+class Solution:
+    def search(self, nums: List[int], target: int) -> int:
+        left = 0
+        right = len(nums) - 1
+        while left <= right:
+            mid = (right + left) // 2
+            if target < nums[mid]:
+                right = mid - 1
+            elif target > nums[mid]:
+                left = mid + 1
+            else:
+                return mid
+        return -1
+
+
+s = Solution()
+# nums = [-1, 0, 2, 4, 6, 8]
+# print(s.search(nums, 4))
+# print(s.search(nums, 3))
+nums = [-1, 0, 3, 5, 9, 12]
+print(s.search(nums, 9))