Introduction

In this blog post, we will explore how to solve the LeetCode problem "3195" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, 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

You are given a 2D binary array grid. Find a rectangle with horizontal and vertical sides with the smallest area, such that all the 1's in grid lie inside this rectangle. Return the minimum possible area of the rectangle. Example 1: Input: grid = [[0,1,0],[1,0,1]] Output: 6 Explanation: The smallest rectangle has a height of 2 and a width of 3, so it has an area of 2 3 = 6. Example 2: Input: grid = [[1,0],[0,0]] Output: 1 Explanation: The smallest rectangle has both height and width 1, so its area is 1 1 = 1. Constraints: 1 <= grid.length, grid[i].length <= 1000 grid[i][j] is either 0 or 1. The input is generated such that there is at least one 1 in grid.

Explanation

Here's a solution to find the minimum area rectangle containing all 1s in a 2D binary array.

• Find Boundaries: Iterate through the grid to find the top-most, bottom-most, left-most, and right-most indices where 1s are present. These define the boundaries of the smallest rectangle containing all 1s.

• Calculate Area: Calculate the height and width of the rectangle using the boundaries found in the previous step. The area is simply the product of the height and width.

• Handle Edge Cases: Be prepared for edge cases, such as when all elements are 0 (which the prompt says won't happen), or when the grid has only one row or column.

• Runtime Complexity: O(m*n), where m is the number of rows and n is the number of columns. Storage Complexity: O(1)

Code

    def minAreaRectangle(grid):
    """
    Finds the minimum area of a rectangle that covers all 1's in a 2D binary array.

    Args:
        grid: A 2D list of integers representing the binary array.

    Returns:
        The minimum possible area of the rectangle.
    """

    top = float('inf')
    bottom = float('-inf')
    left = float('inf')
    right = float('-inf')

    rows = len(grid)
    cols = len(grid[0])

    for i in range(rows):
        for j in range(cols):
            if grid[i][j] == 1:
                top = min(top, i)
                bottom = max(bottom, i)
                left = min(left, j)
                right = max(right, j)

    height = bottom - top + 1
    width = right - left + 1

    return height * width