题解 | #坐标移动#

用字符指针减少拷贝的做法

#include <iostream>
#include <string>
using namespace std;

int StrToNum(const char* num) {
    if (!num) {
        return -1;
    }
    const char* p = num;
    int res = 0;
    while (*p && *p != ';' && *p >= '0' && *p <= '9') {
        res = res * 10 + (*p - '0');
        ++p;
    }
    if (*p != ';') {
        return -1;
    }
    return res;
}

void ParseAction(const char* begin, int* action_x, int* action_y) {
    int steps = StrToNum(begin + 1);
    if (steps <= 0) {
        return;
    }
    switch (*begin) {
        case 'A': *action_x -= steps; break;
        case 'D':  *action_x += steps; break;
        case 'S': *action_y -= steps; break;
        case 'W': *action_y += steps; break;
        default: break;
    }
}

void GetCoordinates(const std::string& actions, int* x, int* y) {
    auto it = actions.begin();
    while (it != actions.end()) {
        ParseAction(&(*it), x, y);
        while (*it && *it++ != ';')
            ;
    }
}

int main() {
    std::string in;
    cin >> in;
    int x = 0, y = 0;
    GetCoordinates(in, &x, &y);
    cout << x << ',' << y << '\n';
}