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）:

1 class Solution { 2 public: 3     bool judgeCircle(string moves) { 4         int LRnum = 0 ; 5         int UDnum = 0 ; 6         for(char c : moves){ 7             if (c == 'U') 8                 UDnum++ ; 9             else if(c == 'D')10                 UDnum--;11             else if(c == 'L')12                 LRnum++;13             else if(c == 'R')14                 LRnum--;15         }16         if(LRnum == 0 && UDnum == 0)17             return true ;18         else19             return false ;20     }21 };

 

Java(15ms):

1 class Solution { 2     public boolean judgeCircle(String moves) { 3         int LRnum = 0 ; 4         int UDnum = 0 ; 5         for(char c : moves.toCharArray()){ 6             if (c == 'U') 7                 UDnum++ ; 8             else if(c == 'D') 9                 UDnum-- ;10             else if(c == 'L')11                 LRnum++ ;12             else if(c == 'R')13                 LRnum-- ;14         }15         return UDnum == 0 && LRnum == 0 ;16     }17 }