index.ts

// const MAX_GRID_Y = 10;
// const MAX_GRID_X = 10;
// const START_POS_Y = 0;
// const START_GRID_X = 0;


interface Coordinate {
  x: number;
  y: number;
}

const MAX_COORD = {
  x: 9,
  y: 9
}

/**
 * Asssume 0,0 is the minimum
 * @param commandsSequence 
 * @param startCoord 
 */
export const isRobotPositionValid = (commandsSequence: string, startCoord: Coordinate): boolean => {

  const robotEndPosition = moveRobot(commandsSequence);
  // check if robots is in the boundary for the box
  return robotEndPosition.y >= 0 && robotEndPosition.y <= MAX_COORD.y && robotEndPosition.x >= 0 && robotEndPosition.x <= MAX_COORD.x;
}

export const moveRobot = (commandsSequence: string): Coordinate => {
  // split commands from string
  const commands = commandsSequence.split(" ");
  const currCoord = { x: 0, y: 0 };
  // for each command move robot
  commands.forEach(command => {
    switch (command) {
      case 'N':
        currCoord.y = currCoord.y + 1;
        break;
      case 'S':
        currCoord.y = currCoord.y - 1;
        break;
      case 'W':
        currCoord.x = currCoord.x - 1;
        break;
      case 'E':
        currCoord.x = currCoord.x + 1;
        break;
    }
  });
  return currCoord;
}


// test cases

test.ts

import { isRobotPositionValid, moveRobot } from '.'

describe("Pairing test", () => {
  it("expect robot to end at 4,4", () => {
    const result = moveRobot("N E N E N E N E");
    expect(result.x).toBe(4);
    expect(result.y).toBe(4);
  })

  it("should return true when the robot is outside the grid", () => {
    const result = isRobotPositionValid("N E N E N E N E", { x: 0, y: 0 });
    expect(result).toBe(true);
  })
  it("should return false when the robot is outside the grid", () => {
    const result = isRobotPositionValid("N W", { x: 0, y: 0 });
    expect(result).toBe(false);
  })
});