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 1: use x,y to record the coordinate.

class Solution {
public:
    bool judgeCircle(string moves) {
        int x=0,y=0;
        for (int i=0;i<moves.length();i++){
            switch(moves[i]){
                case 'U':{++y;break;}                
                case 'D':{--y;break;}
                case 'R':{++x;break;}
                case 'L':{--x;break;}
                default:break;
            }
        }
        return (x==0&&y==0);15     }
};