<p>A robot on an infinite XY-plane starts at point <code>(0, 0)</code> facing north. The robot receives an array of integers <code>commands</code>, which represents a sequence of moves that it needs to execute. There are only three possible types of instructions the robot can receive:</p>

<ul>
	<li><code>-2</code>: Turn left <code>90</code> degrees.</li>
	<li><code>-1</code>: Turn right <code>90</code> degrees.</li>
	<li><code>1 &lt;= k &lt;= 9</code>: Move forward <code>k</code> units, one unit at a time.</li>
</ul>

<p>Some of the grid squares are <code>obstacles</code>. The <code>i<sup>th</sup></code> obstacle is at grid point <code>obstacles[i] = (x<sub>i</sub>, y<sub>i</sub>)</code>. If the robot runs into an obstacle, it will stay in its current location (on the block adjacent to the obstacle) and move onto the next command.</p>

<p>Return the <strong>maximum squared Euclidean distance</strong> that the robot reaches at any point in its path (i.e. if the distance is <code>5</code>, return <code>25</code>).</p>

<p><strong>Note:</strong></p>

<ul>
	<li>There can be an obstacle at <code>(0, 0)</code>. If this happens, the robot will ignore the obstacle until it has moved off the origin. However, it will be unable to return to <code>(0, 0)</code> due to the obstacle.</li>
	<li>North means +Y direction.</li>
	<li>East means +X direction.</li>
	<li>South means -Y direction.</li>
	<li>West means -X direction.</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">commands = [4,-1,3], obstacles = []</span></p>

<p><strong>Output:</strong> <span class="example-io">25</span></p>

<p><strong>Explanation: </strong></p>

<p>The robot starts at <code>(0, 0)</code>:</p>

<ol>
	<li>Move north 4 units to <code>(0, 4)</code>.</li>
	<li>Turn right.</li>
	<li>Move east 3 units to <code>(3, 4)</code>.</li>
</ol>

<p>The furthest point the robot ever gets from the origin is <code>(3, 4)</code>, which squared is <code>3<sup>2</sup> + 4<sup>2 </sup>= 25</code> units away.</p>
</div>

<p><strong class="example">Example 2:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">commands = [4,-1,4,-2,4], obstacles = [[2,4]]</span></p>

<p><strong>Output:</strong> <span class="example-io">65</span></p>

<p><strong>Explanation:</strong></p>

<p>The robot starts at <code>(0, 0)</code>:</p>

<ol>
	<li>Move north 4 units to <code>(0, 4)</code>.</li>
	<li>Turn right.</li>
	<li>Move east 1 unit and get blocked by the obstacle at <code>(2, 4)</code>, robot is at <code>(1, 4)</code>.</li>
	<li>Turn left.</li>
	<li>Move north 4 units to <code>(1, 8)</code>.</li>
</ol>

<p>The furthest point the robot ever gets from the origin is <code>(1, 8)</code>, which squared is <code>1<sup>2</sup> + 8<sup>2</sup> = 65</code> units away.</p>
</div>

<p><strong class="example">Example 3:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">commands = [6,-1,-1,6], obstacles = [[0,0]]</span></p>

<p><strong>Output:</strong> <span class="example-io">36</span></p>

<p><strong>Explanation:</strong></p>

<p>The robot starts at <code>(0, 0)</code>:</p>

<ol>
	<li>Move north 6 units to <code>(0, 6)</code>.</li>
	<li>Turn right.</li>
	<li>Turn right.</li>
	<li>Move south 5 units and get blocked by the obstacle at <code>(0,0)</code>, robot is at <code>(0, 1)</code>.</li>
</ol>

<p>The furthest point the robot ever gets from the origin is <code>(0, 6)</code>, which squared is <code>6<sup>2</sup> = 36</code> units away.</p>
</div>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= commands.length &lt;= 10<sup>4</sup></code></li>
	<li><code>commands[i]</code> is either <code>-2</code>, <code>-1</code>, or an integer in the range <code>[1, 9]</code>.</li>
	<li><code>0 &lt;= obstacles.length &lt;= 10<sup>4</sup></code></li>
	<li><code>-3 * 10<sup>4</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 3 * 10<sup>4</sup></code></li>
	<li>The answer is guaranteed to be less than <code>2<sup>31</sup></code>.</li>
</ul>

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

class Solution {
public:
    struct moveResponse {
        int x, y;
        bool val;

        moveResponse(int x, int y, bool val) {
            this->x = x;
            this->y = y;
            this->val = val;
        }
    };

    char changeDirection(char dir, int cmd) {
        if(cmd == -2) {
            if(dir == 'N') return 'W';
            else if(dir == 'W') return 'S';
            else if(dir == 'S') return 'E';
            else return 'N';
        }
        if(dir == 'N') return 'E';
        else if(dir == 'E') return 'S';
        else if(dir == 'S') return 'W';
        else return 'N';
    }

    moveResponse move(int x, int y, int k, char dir, map<pair<int, int>, int> &obs) {
        if(dir == 'N') {
            for(int i = 1; i <= k; i++) {
                if(obs[make_pair(x, y + i)] != 0) {
                    return moveResponse(x, y + (i - 1), false);
                }
            }
            return moveResponse(x, y + k, true);
        } else if(dir == 'E') {
            for(int i = 1; i <= k; i++) {
                if(obs[make_pair(x + i, y)] != 0) {
                    return moveResponse(x + (i - 1), y, false);
                }
            }
            return moveResponse(x + k, y, true);
        } else if(dir == 'S') {
            for(int i = 1; i <= k; i++) {
                if(obs[make_pair(x, y - i)] != 0) {
                    return moveResponse(x, y - (i - 1), false);
                }
            }
            return moveResponse(x, y - k, true);
        }
        for(int i = 1; i <= k; i++) {
            if(obs[make_pair(x - i, y)] != 0) {
                return moveResponse(x - (i - 1), y, false);
            }
        }
        return moveResponse(x - k, y, true);
    }

    int robotSim(vector<int>& commands, vector<vector<int>>& obstacles) {
        map<pair<int, int>, int> obs;
        int mx = -1;
        for(auto &i : obstacles) 
            obs[make_pair(i.front(), i.back())] += 1;

        int x = 0, y = 0;
        char dir = 'N';

        for(int cmd : commands) {
            cout << x << " " << y << " " << dir << endl;
            if(cmd == -2 || cmd == -1) {
                dir = changeDirection(dir, cmd);
                continue;
            }
            moveResponse m = move(x, y, cmd, dir, obs);
            x = m.x, y = m.y;
            mx = max(mx, x*x + y*y);
        }
        return mx;
    }
};
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