题目描述：

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 解题思路： 统计输入字符串中字符U和D的个数是否一样，L和R个数是否一样，若都一样，则返回到起点。 代码：

1 class Solution { 2 public: 3     bool judgeCircle(string moves) { 4          5         int u = 0; 6         int d = 0; 7         int l = 0; 8         int r = 0; 9         u = std::count(moves.begin(), moves.end(), 'U');10         d = std::count(moves.begin(), moves.end(), 'D');11         l = std::count(moves.begin(), moves.end(), 'L');12         r = std::count(moves.begin(), moves.end(), 'R');13         return (u == d) && (l == r);   14     }15 };