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

Solution:

If we can move back to the origin, numbers of "U" should be the same with numbers of "D", while numbers of "L" should be the same with numbers of "R".


Code:

public class Solution {
    public boolean judgeCircle(String moves) {
        int vertical = 0;
        int horizontal = 0;
        for (char c : moves.toCharArray()) {
            if (c == 'U') {
                vertical++;
            }
            if (c == 'D') {
                vertical--;
            }
            if (c == 'R') {
                horizontal++;
            }
            if (c == 'L') {
                horizontal--;
            }
        }
        return vertical == 0 && horizontal == 0;
    }
}