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

题目的要求是假定一个机器人在原点（0,0），根据给定的字符串，往不同的方向移动，判断最后机器人是否回到原点。不同的字母代表不同的方向：

L：左，R：右，U：上，D：下。

思路很简单，遍历字符串，按照字符串的方向指示移动一遍，判断最后机器人是否仍然在原位即可：

class Solution {public:    bool judgeCircle(string moves) {        int x = 0, y = 0;        for (int i = 0; i < moves.size(); i++) {            switch (moves[i]) {                case 'U':                    y += 1;                    break;                case 'D':                    y -= 1;                    break;                case 'L':                    x -= 1;                    break;                case 'R':                    x += 1;                    break;            }        }        if (x == 0 && y == 0)            return true;        else            return false;    }};