Introduction

In this blog post, we will explore how to solve the LeetCode problem "2596" 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

There is a knight on an n x n chessboard. In a valid configuration, the knight starts at the top-left cell of the board and visits every cell on the board exactly once. You are given an n x n integer matrix grid consisting of distinct integers from the range [0, n n - 1] where grid[row][col] indicates that the cell (row, col) is the grid[row][col]th cell that the knight visited. The moves are 0-indexed. Return true if grid represents a valid configuration of the knight's movements or false otherwise. Note that a valid knight move consists of moving two squares vertically and one square horizontally, or two squares horizontally and one square vertically. The figure below illustrates all the possible eight moves of a knight from some cell. Example 1: Input: grid = [[0,11,16,5,20],[17,4,19,10,15],[12,1,8,21,6],[3,18,23,14,9],[24,13,2,7,22]] Output: true Explanation: The above diagram represents the grid. It can be shown that it is a valid configuration. Example 2: Input: grid = [[0,3,6],[5,8,1],[2,7,4]] Output: false Explanation: The above diagram represents the grid. The 8th move of the knight is not valid considering its position after the 7th move. Constraints: n == grid.length == grid[i].length 3 <= n <= 7 0 <= grid[row][col] < n n All integers in grid are unique.

Explanation

Here's the breakdown of the solution:

• Find Coordinates: Locate the coordinates (row, col) for each number from 0 to n*n-1 in the grid.
• Validate Moves: Iterate through the numbers from 0 to n*n-2. For each consecutive pair of numbers, check if the move from the first number's coordinates to the second number's coordinates is a valid knight move.

• Early Exit: If any move is invalid, return False immediately. If all moves are valid, return True.

• Runtime & Storage Complexity: The runtime complexity is O(n^2), where n is the dimension of the grid, to iterate through the matrix. The storage complexity is O(n^2) to store the coordinates of each number.

Code

    def checkValidGrid(grid):
    n = len(grid)
    positions = {}
    for r in range(n):
        for c in range(n):
            positions[grid[r][c]] = (r, c)

    def is_valid_move(r1, c1, r2, c2):
        dr = abs(r1 - r2)
        dc = abs(c1 - c2)
        return (dr == 2 and dc == 1) or (dr == 1 and dc == 2)

    for i in range(n * n - 1):
        r1, c1 = positions[i]
        r2, c2 = positions[i + 1]
        if not is_valid_move(r1, c1, r2, c2):
            return False

    return True