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 tothe original place.

The move sequence is represented by a string. And each move is represent by a character. The valid robot moves areR(Right),L(Left),U(Up) andD(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

S:

    bool judgeCircle(string moves) {
        int left = 0, up = 0;
        for (char c : moves) {
            switch (c) {
                case 'U' : up++;
                    break;
                case 'D' : up--;
                    break;
                case 'L' : left++;
                    break;
                case 'R' : left--;
                    break;
            }
        }
        return left == 0 && up == 0;
    }