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

Example 1:

Input: "UD"
Output: true

Example 2:

Input: "LL"
Output: false

思路：
可以模擬移動，對x，y進行增減。也可以直接比較U-D L-F的對數是否一直。
JAVA CODE

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

Judge Route Circle