Introduction

In this blog post, we will explore how to solve the LeetCode problem "1496" 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

Given a string path, where path[i] = 'N', 'S', 'E' or 'W', each representing moving one unit north, south, east, or west, respectively. You start at the origin (0, 0) on a 2D plane and walk on the path specified by path. Return true if the path crosses itself at any point, that is, if at any time you are on a location you have previously visited. Return false otherwise. Example 1: Input: path = "NES" Output: false Explanation: Notice that the path doesn't cross any point more than once. Example 2: Input: path = "NESWW" Output: true Explanation: Notice that the path visits the origin twice. Constraints: 1 <= path.length <= 104 path[i] is either 'N', 'S', 'E', or 'W'.

Explanation

Here's the breakdown of the solution:

• Core Idea: Keep track of visited coordinates using a set. For each move, calculate the new coordinate. If the new coordinate is already in the visited set, the path crosses itself.
• Coordinate Tracking: Start at (0, 0). Update the coordinates based on the direction ('N', 'S', 'E', 'W').

• Early Exit: If a coordinate is revisited, immediately return True. If the entire path is traversed without revisiting, return False.

• Complexity: O(n) runtime, O(n) storage where n is the length of the path.

Code

    def isPathCrossing(path: str) -> bool:
    """
    Checks if a given path crosses itself on a 2D plane.

    Args:
        path: A string representing the path, where each character is 'N', 'S', 'E', or 'W'.

    Returns:
        True if the path crosses itself, False otherwise.
    """

    visited = {(0, 0)}  # Initialize with the starting point
    x, y = 0, 0

    for move in path:
        if move == 'N':
            y += 1
        elif move == 'S':
            y -= 1
        elif move == 'E':
            x += 1
        else:  # move == 'W'
            x -= 1

        current_coordinate = (x, y)

        if current_coordinate in visited:
            return True

        visited.add(current_coordinate)

    return False