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

很簡單的一題，估計(jì)是AC率最高的一題了吧。

class Solution {
    public boolean judgeCircle(String moves) {
        if(moves==null||moves.length()==0)
            return false;
             int upCount = 0 ;
            int rightCount = 0 ;
        for(int i = 0 ;i<moves.length();i++)
        {
            char ch = moves.charAt(i);
            switch(ch)
            {
               case('U'): upCount++;
                    break;
              case('D'):
                  upCount--;
                    break;
              case('R'):
                  rightCount++;
                    break;
              case('L'):    
                  rightCount--;
                    break;
                default:
                   break;
            }
            
        }
        return upCount==0&&rightCount==0;
    }
}