Leetcode 657. Judge Route Circle

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

Code (Java):

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

class Solution {     public boolean judgeCircle(String moves) {         if (moves == null || moves.length() == 0) {             return true;         }                   int x = 0;         int y = 0;                   for (int i = 0; i < moves.length(); i++) {             char move = moves.charAt(i);             switch (move) {                 case 'U':                     y++;                     break;                 case 'D':                     y--;                     break;                 case 'L':                     x--;                     break;                 case 'R':                     x++;                     break;             }         }                   return x == 0 && y == 0;     } }