# LeetCode - 0874. Walking Robot Simulation
### 題目網址：https://leetcode.com/problems/walking-robot-simulation/
###### tags: `LeetCode` `Easy` `模擬`

/*
    -LeetCode format-
    Problem: 874. Walking Robot Simulation
    Difficulty: Easy
    
    by Inversionpeter
*/



class Solution {
public:
    int robotSim(vector<int>& commands, vector<vector<int>>& obstacles) {
        int nowX = 0, nowY = 0, dx[4] = { 0, 1, 0, -1 }, dy[4] = { 1, 0, -1, 0 }, direction = 0, maximum = 0;
        map <pair<int, int>, bool> isBlocked;
        for (int i = 0; i != obstacles.size(); ++i)
            isBlocked[{ obstacles[i][0], obstacles[i][1] }] = true;
        for (int &i : commands) {
            if (i == -1)
                direction = (direction + 1) & 3;
            else if (i == -2)
                direction = (direction + 3) & 3;
            else {
                for (int j = 0; j < i; ++j) {
                    nowX += dx[direction]; nowY += dy[direction];
                    if (isBlocked[{ nowX, nowY }]) {
                        nowX -= dx[direction]; nowY -= dy[direction];
                        break;
                    }
                }
            }
            maximum = max(maximum, nowX * nowX + nowY * nowY);
        }
        return maximum;
    }
};