657. Judge Route Circle

nitially, 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 tothe 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

class Solution {

    public boolean judgeCircle(String moves) {

        int x = 0;

        int y = 0;

        for (char ch : moves.toCharArray()) {

            if (ch == 'U')

                y++;

            if (ch == 'D')

                y--;

            if (ch == 'L')

                x--;

            if (ch == 'R')

                x++;

        }

        return x == 0 && y== 0; //检查是否回到了起点处

    }

}