Time: 5 ms (57.49%), Space: 7.1 MB (64.25%) - LeetHub

Author: knockcat

0980-unique-paths-iii/0980-unique-paths-iii.cpp

@@ -0,0 +1,35 @@
+class Solution {
+public:
+    int res = 0, empty = 1;
+    void dfs(vector<vector<int>>& grid, int x, int y, int count) {
+        if (x < 0 || x >= grid.size() || y < 0 || y >= grid[0].size() || grid[x][y] == -1) return;
+        
+        if (grid[x][y] == 2) {
+            if(empty == count) res++; 
+            return;
+        }
+        
+        grid[x][y] = -1;
+        
+        dfs(grid, x+1, y, count+1);
+        dfs(grid, x-1, y, count+1);
+        dfs(grid, x, y+1, count+1);
+        dfs(grid, x, y-1, count+1);
+        
+        grid[x][y] = 0;
+        
+    }
+    
+    int uniquePathsIII(vector<vector<int>>& grid) {
+        int start_x, start_y;
+        for (int i = 0; i < grid.size(); i++) {
+            for (int j = 0; j < grid[0].size(); j++) {
+                if (grid[i][j] == 1) start_x = i, start_y = j;
+                else if (grid[i][j] == 0) empty++;
+            }
+        }
+        
+        dfs(grid, start_x, start_y, 0);
+        return res;
+    }
+};