# Solving Leetcode Interviews in Seconds with AI: Valid Perfect Square


	# Introduction
	In this blog post, we will explore how to solve the LeetCode problem "367" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like [Chatmagic](https://www.chatmagic.app), we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

	# Problem Statement
	> Given a positive integer num, return true if num is a perfect square or false otherwise. A perfect square is an integer that is the square of an integer. In other words, it is the product of some integer with itself. You must not use any built-in library function, such as sqrt.   Example 1:  Input: num = 16 Output: true Explanation: We return true because 4 * 4 = 16 and 4 is an integer.  Example 2:  Input: num = 14 Output: false Explanation: We return false because 3.742 * 3.742 = 14 and 3.742 is not an integer.    Constraints:  1 <= num <= 231 - 1  

	# Explanation
	Here's the solution to determine if a number is a perfect square without using built-in square root functions:

*   **Binary Search:** Employ binary search on the range `[1, num]` to efficiently find the potential square root.
*   **Midpoint Check:** In each iteration, calculate the square of the midpoint. If the square equals `num`, return `true`.
*   **Adjust Search Range:** If the square is less than `num`, narrow the search to the upper half. Otherwise, narrow it to the lower half. If the binary search completes without finding an exact square, return `false`.

*   **Runtime Complexity:** O(log n), where n is the input number `num`. **Storage Complexity:** O(1).

	
	# Code
	```python
	def isPerfectSquare(num: int) -> bool:
    """
    Given a positive integer num, return true if num is a perfect square or false otherwise.
    You must not use any built-in library function, such as sqrt.

    Example 1:
    Input: num = 16
    Output: true
    Explanation: We return true because 4 * 4 = 16 and 4 is an integer.

    Example 2:
    Input: num = 14
    Output: false
    Explanation: We return false because 3.742 * 3.742 = 14 and 3.742 is not an integer.

    Constraints:
    1 <= num <= 231 - 1
    """

    left, right = 1, num

    while left <= right:
        mid = left + (right - left) // 2
        square = mid * mid

        if square == num:
            return True
        elif square < num:
            left = mid + 1
        else:
            right = mid - 1

    return False
	```