0657-robot-return-to-origin.js

/**
 * 657. Robot Return to Origin
 * https://leetcode.com/problems/robot-return-to-origin/
 * Difficulty: Easy
 *
 * There is a robot starting at the position (0, 0), the origin, on a 2D plane. Given a sequence
 * of its moves, judge if this robot ends up at (0, 0) after it completes its moves.
 *
 * You are given a string moves that represents the move sequence of the robot where moves[i]
 * represents its ith move. Valid moves are 'R' (right), 'L' (left), 'U' (up), and 'D' (down).
 *
 * Return true if the robot returns to the origin after it finishes all of its moves, or false
 * otherwise.
 *
 * Note: The way that the robot is "facing" is irrelevant. 'R' will always make the robot move
 * to the right once, 'L' will always make it move left, etc. Also, assume that the magnitude
 * of the robot's movement is the same for each move.
 */

/**
 * @param {string} moves
 * @return {boolean}
 */
/**
 * @param {string} moves
 * @return {boolean}
 */
var judgeCircle = function(moves) {
  let x = 0;
  let y = 0;

  for (const move of moves) {
    x += move === 'R' ? 1 : move === 'L' ? -1 : 0;
    y += move === 'U' ? 1 : move === 'D' ? -1 : 0;
  }

  return x === 0 && y === 0;
};