Create shortest-path-to-get-food.cpp

Author: kamyu104

C++/shortest-path-to-get-food.cpp

@@ -0,0 +1,42 @@
+// Time:  O(m * n)
+// Space: O(m + n)
+
+class Solution {
+public:
+    int getFood(vector<vector<char>>& grid) {
+        static const vector<pair<int, int>> directions{{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
+        
+        vector<pair<int, int>> q;
+        for (int r = 0; r < size(grid); ++r) {
+            for (int c = 0; c < size(grid[0]); ++c) {
+                if (grid[r][c] == '*') {
+                    q.emplace_back(r, c);
+                    break;
+                }
+            }
+        }
+        
+        int result = 0;
+        while (!empty(q)) {
+            ++result;
+            vector<pair<int, int>> new_q;
+            for (const auto& [r, c] : q) {
+                for (const auto& [dr, dc] : directions) {
+                    int nr = r + dr, nc = c + dc;
+                    if (!(0 <= nr && nr < size(grid) &&
+                          0 <= nc && nc < size(grid[0]) &&
+                          grid[nr][nc] != 'X')) {
+                        continue;
+                    }
+                    if (grid[nr][nc] == '#') {
+                        return result;
+                    }
+                    grid[nr][nc] = 'X';
+                    new_q.emplace_back(nr, nc);
+                }
+            }
+            q = move(new_q);
+        }
+        return -1;
+    }
+};