Pacific Atlantic Water Flow solution

Author: PDKhan

pacific-atlantic-water-flow/PDKhan.cpp

@@ -0,0 +1,40 @@
+class Solution {
+    public:
+        void dfs(int prev, int r, int c, vector<vector<int>>& heights, vector<vector<bool>>& visit){
+            if(r < 0 || c < 0 || r >= heights.size() || c >= heights[0].size() || visit[r][c] || heights[r][c] < prev)
+                return;
+            
+            visit[r][c] = true;
+    
+            dfs(heights[r][c], r - 1, c, heights, visit);
+            dfs(heights[r][c], r + 1, c, heights, visit);
+            dfs(heights[r][c], r, c - 1, heights, visit);
+            dfs(heights[r][c], r, c + 1, heights, visit);
+        }
+    
+        vector<vector<int>> pacificAtlantic(vector<vector<int>>& heights) {
+            vector<vector<int>> result;
+            vector<vector<bool>> pacific(heights.size(), vector(heights[0].size(), false));
+            vector<vector<bool>> atlantic(heights.size(), vector(heights[0].size(), false));
+    
+            for(int i = 0; i < heights.size(); i++){
+                dfs(heights[i][0], i, 0, heights, pacific);
+                dfs(heights[i][heights[0].size()-1], i, heights[0].size()-1, heights, atlantic);
+            }
+    
+            for(int j = 0; j < heights[0].size(); j++){
+                dfs(heights[0][j], 0, j, heights, pacific);
+                dfs(heights[heights.size()-1][j], heights.size()-1, j, heights, atlantic);
+            }
+    
+            for(int i = 0; i < heights.size(); i++){
+                for(int j = 0; j < heights[0].size(); j++){
+                    if(pacific[i][j] && atlantic[i][j]){
+                        result.push_back({i, j});
+                    }
+                }
+            }
+    
+            return result;
+        }
+    };