Judge Route Circle

Easy Game

LeetCode: https://leetcode.com/contest/leetcode-weekly-contest-45/problems/judge-route-circle/

Question

Initially, there is a Robot at position (0, 0). Given a sequence of its moves, judge if this robot makes a circle, which means it moves back to the original place.

The move sequence is represented by a string. And each move is represent by a character. The valid robot moves are R (Right), L (Left), U (Up) and D (down). The output should be true or false representing whether the robot makes a circle.

Example 1:

Input: "UD"
Output: true

Example 2:

Input: "LL"
Output: false

Solution

Java

public class Solution {
    public boolean judgeCircle(String moves) {
        int rd = 0;
        int dd = 0;
        for (int i = 0; i < moves.length(); i++) {
            char direct = moves.charAt(i);
            switch (direct) {
                case 'L':
                    --rd;
                    break;
                case 'R':
                    ++ rd;
                    break;
                case 'U':
                    --dd;
                    break;
                case 'D':
                    ++dd;
                    break;
            }
        }
        return rd == 0 && dd == 0;
    }
}