MediumTrees

Validate Binary Search Tree

Check if tree is valid BST

Solution Approach

Divide search space in half repeatedly. Apply binary search on sorted arrays or search space. Check middle element and adjust bounds based on comparison.

Implementation

def search(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

Complexity Analysis

Time Complexity

O(log n)

Space Complexity

O(1)

Key Learning Points

Divide search space by 2Only works on sorted dataPrevent integer overflow with mid calculation