Roomba - Amazon Top Interview Questions

Problem Statement :

A Roomba robot is currently sitting in a Cartesian plane at (0, 0). You are given a list of its moves that it will make, containing NORTH, SOUTH, WEST, and EAST.

Return whether after its moves it will end up in the coordinate (x, y).


n ≤ 100,000 where n is length of moves

Example 1


moves = ["NORTH", "EAST"]
x = 1
y = 1




Moving north moves it to (0, 1) and moving east moves it to (1, 1)

Example 2


moves = ["WEST", "EAST"]
x = 1
y = 0



This Roomba will end up at (0, 0)

Solution :

                        Solution in C++ :

bool solve(vector<string>& moves, int x, int y) {
    for (auto& move : moves) {
        if (move.front() == 'N')
        else if (move.front() == 'S')
        else if (move.front() == 'W')
        else if (move.front() == 'E')
    if (!x && !y) return true;
    return false;

                        Solution in Java :

import java.util.*;

class Solution {
    public boolean solve(String[] moves, int ax, int ay) {
        String px = "EAST";
        String nx = "WEST";
        String py = "NORTH";
        String ny = "SOUTH";
        int x = 0;
        int y = 0;
        for (int i = 0; i < moves.length; i++) {
            if (moves[i].equals(px)) {

            if (moves[i].equals(nx)) {
            if (moves[i].equals(py)) {

            if (moves[i].equals(ny)) {
        if (x == ax && ay == y)
            return true;
            return false;

                        Solution in Python : 
class Solution:
    def solve(self, moves, x, y):
        currX, currY = 0, 0
        d = {
            "EAST": (1, 0),
            "WEST": (-1, 0),
            "NORTH": (0, 1),
            "SOUTH": (0, -1),
        for i in moves:
            dx, dy = d[i]
            currX += dx
            currY += dy
        if currX == x and currY == y:
            return True
        return False

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