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

UDLR表示机器人的上下左右，判断它能否回到原点

C++（19ms）:

class Solution {
public:
    bool judgeCircle(string moves) {
        int LRnum = 0 ;
        int UDnum = 0 ;
        for(char c : moves){
            if (c == 'U')
                UDnum++ ;
            else if(c == 'D')
                UDnum--;
            else if(c == 'L')
                LRnum++;
            else if(c == 'R')
                LRnum--;
        }
        if(LRnum == 0 && UDnum == 0)
            return true ;
        else
            return false ;
    }
};

Java(15ms):

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