657.机器人回原点

题目：[https://leetcode-cn.com/problems/robot-return-to-origin/description/]
思路：直接模拟,记录相应字符出现的次数、统计最后的情况；

class Solution {
public:
    bool judgeCircle(string moves) {
        vector<int> step(4,0);
        for(decltype(moves.size()) i=0;i!=moves.size();++i)
        {
            switch (moves[i])
            {
                case'R':++step[0];break;
                case'L':++step[1];break;
                case'U':++step[2];break;
                case'D':++step[3];break;
            }
        }
        return (step[0]-step[1]+step[2]-step[3]==0)?1:0;
    }
};