Create a function that checks if a given path, represented by 'N', 'S', 'E', 'W', crosses itself at any point on a 2D plane.

Gulshan KumarGulshan Kumar
2 min read

Q - 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.

LeetCode Problem: Link | Click Here

class Solution {
    public boolean isPathCrossing(String path) {

        // Calculate the length of the input path
        int pathLength = path.length();

        // Create an array to store visited coordinates, initialized with pathLength+1 capacity
        String[] pathCrossed =  new String[pathLength + 1];

        // Initialize variables to track current coordinates and result status
        boolean result = false;
        int xCoordinate = 0;
        int yCoordinate = 0;

        // Start position is at (0,0)
        pathCrossed[0] = "0,0";

        // Iterate through each character in the input path
        for (int i = 0; i < pathLength; i++){

            // Update coordinates based on the direction specified in the path
            if (path.charAt(i) == 'N'){
                yCoordinate++;
            } else if (path.charAt(i) == 'E') {
                xCoordinate++;
            } else if (path.charAt(i) == 'S') {
                yCoordinate--;
            } else if (path.charAt(i) == 'W') {
                xCoordinate--;
            }

            // Create a string representing current coordinates (x,y)
            String check = xCoordinate + "," + yCoordinate;

            // Check if the current coordinates have been visited before
            for (int j = 0; j <= i; j++) {
                if (check.equals(pathCrossed[j])) {
                    result = true; // Set result to true if the coordinates are revisited
                    break; // Exit the loop once a match is found
                }
            }

            // If result is true, no need to continue checking, break from the loop
            if (result) {
                break;
            }

            // Store the current coordinates in the visited path array
            pathCrossed[i + 1] = xCoordinate + "," + yCoordinate;
        }

        return result; // Return the final result indicating if the path crosses itself
    }
}
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Written by

Gulshan Kumar
Gulshan Kumar

As a Systems Engineer at Tata Consultancy Services, I deliver exceptional software products for mobile and web platforms, using agile methodologies and robust quality maintenance. I am experienced in performance testing, automation testing, API testing, and manual testing, with various tools and technologies such as Jmeter, Azure LoadTest, Selenium, Java, OOPS, Maven, TestNG, and Postman. I have successfully developed and executed detailed test plans, test cases, and scripts for Android and web applications, ensuring high-quality standards and user satisfaction. I have also demonstrated my proficiency in manual REST API testing with Postman, as well as in end-to-end performance and automation testing using Jmeter and selenium with Java, TestNG and Maven. Additionally, I have utilized Azure DevOps for bug tracking and issue management.