class Solution {
public:
int robotSim(vector<int>& commands, vector<vector<int>>& obstacles) {
constexpr int dirs[4][2] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
int ans = 0;
int d = 0; // 0 := north, 1 := east, 2 := south, 3 := west
int x = 0; // the start x
int y = 0; // the start y
unordered_set<pair<int, int>, PairHash> obstaclesSet;
for (const vector<int>& o : obstacles)
obstaclesSet.insert({o[0], o[1]});
for (const int c : commands) {
if (c == -1) {
d = (d + 1) % 4;
} else if (c == -2) {
d = (d + 3) % 4;
} else {
for (int step = 0; step < c; ++step) {
if (obstaclesSet.count({x + dirs[d], y + dirs[d + 1]}))
break;
x += dirs[d];
y += dirs[d + 1];
}
}
ans = max(ans, x * x + y * y);
}
return ans;
}
private:
struct PairHash {
size_t operator()(const pair<int, int>& p) const {
return p.first ^ p.second;
}
};
};