657. Judge Route Circle【easy】

657. Judge Route Circle【easy】

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

解法一：

 class Solution {
 public:
     bool judgeCircle(string moves) {
         int h = ;
         int w = ;

         for (int i = ; i < moves.length(); ++i) {
             if (moves[i] == 'U') {
                 h++;
             } else if (moves[i] == 'D') {
                 h--;
             } else if (moves[i] == 'R') {
                 w++;
             } else if (moves[i] == 'L') {
                 w--;
             }
         }

         return (h ==  && w == );
     }
 };

解法二：

 class Solution {
 public:
     bool judgeCircle(string moves) {
         unordered_map<char, int> c;
         for ( char m : moves )
             ++c[m];
         return c['L'] == c['R'] && c['U'] == c['D'];
     }
 };

参考@zqfan 的代码。