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994.rotting-oranges.cpp

+/*
+ * @lc app=leetcode id=994 lang=cpp
+ *
+ * [994] Rotting Oranges
+ */
+
+// @lc code=start
+class Solution
+{
+    int m = 0;
+    int n = 0;
+    //bool anyFresh = false;
+    int time = 0;
+    int numFresh = 0;
+    vector<pair<int, int>> dirs = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
+
+public:
+    int orangesRotting(vector<vector<int>> &grid)
+    {
+        this->m = grid.size();
+        this->n = grid[0].size();
+        queue<pair<int, int>> q;
+
+        for (int i = 0; i < m; ++i)
+        {
+            for (int j = 0; j < n; ++j)
+            {
+                // 0-> empty
+                // 1-> fresh
+                // 2->rotton
+                // 3-> visited
+                if (grid[i][j] == 2)
+                {
+                    q.push({i, j});
+                }
+                else if (grid[i][j] == 1)
+                    numFresh++;
+            } //for
+        }     //for
+
+        while (!q.empty() && numFresh > 0)
+        {
+            //bool rotton = false;
+            int len = q.size();
+            for (int i = 0; i < len; ++i)
+            {
+                auto [curr_x, curr_y] = q.front();
+                q.pop();
+
+                for (auto &dir : dirs)
+                {
+                    int n_x = curr_x + dir.first;
+                    int n_y = curr_y + dir.second;
+                    if (n_x >= m || n_x < 0 || n_y < 0 || n_y >= n)
+                        continue;
+                    if (grid[n_x][n_y] == 1)
+                    {
+                        //rotton = true;
+                        grid[n_x][n_y] = 3;
+                        q.push({n_x, n_y});
+                        numFresh--;
+                    }
+                } //for
+            }     //for
+            time++;
+        } //while
+
+        if (numFresh > 0)
+            return -1;
+
+        return this->time;
+    }
+};
+// @lc code=end