Path Finder #4: where are you?

• Time : $O(|s|)$
• Space : $O(1)$

c++

using namespace std;

int dx[4]{-1, 0, 1, 0}, dy[4]{0, 1, 0, -1};

struct State {
    int x = 0,y = 0;
    int dir = 0;
}state;

std::vector<int> i_am_here(std::string path) {
    int step = 0;
    for(char x : path) {
        if(!isdigit(x)) {
            state.x += dx[state.dir] * step;
            state.y += dy[state.dir] * step;
            step = 0;
        } else step = step * 10 + (x - '0');
        
        if(x == 'r') state.dir = (state.dir + 1) % 4;
        else if(x == 'l') state.dir = (state.dir - 1 + 4) % 4;
        else if(x == 'R') state.dir = (state.dir + 2) % 4;
        else if(x == 'L') state.dir = (state.dir + 2) % 4;
    }
    state.x += dx[state.dir] * step;
    state.y += dy[state.dir] * step;
    return {state.x,state.y};
}