JudgeRouteCircle.java

/**
 * Created by Yang on 2017/8/19.
 ************************************************************************************************
 * 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
 ************************************************************************************************
 */
public class JudgeRouteCircle {
    public boolean judgeCircle(String moves) {
        int x = 0;
        int y = 0;
        for (int i = 0; i < moves.length(); i++) {
            switch (moves.charAt(i)) {
                case 'U':
                    y++;
                    break;
                case 'D':
                    y--;
                    break;
                case 'L':
                    x--;
                    break;
                case 'R':
                    x++;
                    break;
            }
        }
        return x == 0 && y == 0;
    }
}