有限自动机（DFA）

因为没想起来用C++的find()函数来分割字符串，就直接用 DFA（有限自动机）的模板来做了，没想到竟然一次性通过了！用DFA的好处是代码比较简洁，不容易遗漏情况，可惜我用的还不太熟练，所以写的有点慢......最后，状态转换的表格见代码末尾

#include <iostream>
#include <unordered_map>
#include <vector>
using namespace std;

struct Cord
{
    int x, y;
};

unordered_map<char, Cord> dir= {{'A', {-1, 0}}, {'D', {1, 0}}, 
                                {'W', {0, 1}},  {'S', {0, -1}}};

class Automaton
{
    enum State {s_end, s_num, s_char, s_bad};
    unordered_map<State, vector<State>> ns = {
        {s_end,   {s_char,    s_bad,   s_end,    s_bad}},
        {s_num,   {s_bad,     s_num,   s_end,    s_bad}},
        {s_char,  {s_bad,     s_num,   s_end,    s_bad}},
        {s_bad,   {s_bad,     s_bad,   s_end,    s_bad}}
    };

    int get_col(char c)
    {
        if (c == ';')
            return 2;
        else if (c <= '9' && c >= '0')
            return 1;
        else if (dir.find(c) != dir.end())
            return 0;
        else
            return 3;
    }
public:
    State state = s_end;
    int num = 0;
    char d;
    Cord cord = {0, 0};
    void get(char c)
    {
        int col = get_col(c);
        State old = state;
        state = ns[state][col];
        if (state == s_end)
        {
            if (old == s_num && num < 100)
            {
                cord.x += dir[d].x * num;
                cord.y += dir[d].y * num;
            }
            num = 0;
        }
        else if (state == s_char)
        {
            d = c;
        }
        else if (state == s_num)
        {
            num = num * 10 + c - '0';
        }
    }
};

int main() {
    
    string s;
    getline(cin, s);
    Automaton am;
    for (auto c : s)
    {
        am.get(c);
    }
    cout << am.cord.x << ',' << am.cord.y;
}

/* 
        ADWS    0~9     ;       other
s_end   s_char  s_bad   s_end   s_bad
s_num   s_bad   s_num   s_end   s_bad
s_char  s_bad   s_num   s_end   s_bad
s_bad   s_bad   s_bad   s_end   s_bad

*/