Description
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.
Example 1:
Input: moves = "UD" Output: true Explanation: The robot moves up once, and then down once. All moves have the same magnitude, so it ended up at the origin where it started. Therefore, we return true.
Example 2:
Input: moves = "LL" Output: false Explanation: The robot moves left twice. It ends up two "moves" to the left of the origin. We return false because it is not at the origin at the end of its moves.
Constraints:
1 <= moves.length <= 2 * 104movesonly contains the characters'U','D','L'and'R'.
Solutions
This solution tracks the robot's x and y coordinates while iterating through the moves, incrementing or decrementing based on direction (R/L for horizontal, U/D for vertical). It returns true if both coordinates are 0 at the end, confirming the robot completed a circular path back to the starting position.
/**
* @param {string} moves
* @return {boolean}
*/
var judgeCircle = function(moves) {
let x = 0;
let y = 0;
for (const move of moves) {
if (move === 'R') {
x++;
} else if (move === 'L') {
x--;
} else if (move === 'U') {
y++;
} else if (move === 'D') {
y--;
}
}
return x === 0 && y === 0;
};