Create walking-robot-simulation.cpp

Author: kamyu104

C++/walking-robot-simulation.cpp

@@ -0,0 +1,44 @@
+// Time:  O(n + k)
+// Space: O(k)
+
+class Solution {
+private:
+    template <typename T>
+    struct PairHash {
+        size_t operator()(const pair<T, T>& p) const {
+            size_t seed = 0;
+            seed ^= std::hash<T>{}(p.first)  + 0x9e3779b9 + (seed<<6) + (seed>>2);
+            seed ^= std::hash<T>{}(p.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
+            return seed;
+        }
+    };
+
+public:
+    int robotSim(vector<int>& commands, vector<vector<int>>& obstacles) {
+        static const vector<pair<int, int>> directions{{0, 1}, {1, 0},
+                                                       {0, -1}, {-1, 0}};
+        unordered_set<pair<int, int>, PairHash<int>> lookup;
+        for (const auto& obstacle: obstacles) {
+            lookup.emplace(obstacle[0], obstacle[1]);
+        }
+        int result = 0;
+        int x = 0, y = 0, i = 0;
+        for (const auto& cmd: commands) {
+            if (cmd == -2) {
+                i = (i - 1 + 4) % 4;
+            } else if (cmd == -1) {
+                i = (i + 1) % 4;
+            } else {
+                for (int k = 0; k < cmd; ++k) {
+                    if (!lookup.count(make_pair(x + directions[i].first,
+                                                y + directions[i].second))) {
+                        x += directions[i].first;
+                        y += directions[i].second;
+                        result = max(result, x * x + y * y);
+                    }
+                }
+            }
+        }
+        return result;
+    }
+};