Time: 604 ms (16.65%), Space: 115.6 MB (26.66%) - LeetHub

Author: knockcat

1905-count-sub-islands/1905-count-sub-islands.cpp

@@ -5,45 +5,23 @@ class Solution {
         int n = grid1.size();
         int m = grid1[0].size();
 
-        vector<vector<bool>> visited(n, vector<bool>(m, false)), visited2(n, vector<bool>(m, false));
+        vector<vector<bool>> visited(n, vector<bool>(m, false));
 
-        function<void(int, int)> dfs = [&](int i, int j)
-        {
-            if(i < 0 or j < 0 or i >= n or j >= m or visited[i][j] or !grid1[i][j])
-                return;
-            
-            visited[i][j] = 1;
-            
-            dfs(i-1, j);
-            dfs(i, j+1);
-            dfs(i+1, j);
-            dfs(i, j-1);
-        };
-        
-        for(int i = 0; i < n; ++i)
-        {
-            for(int j = 0; j < m; ++j)
-            {
-                if(!visited[i][j] and grid1[i][j])
-                    dfs(i, j);
-            }
-        }
-        
-        function<bool(int, int)> dfs2 = [&](int i, int j) -> bool{
-            if(i < 0 or j < 0 or i >= n or j >= m or visited2[i][j] or !grid2[i][j])
+        function<bool(int, int)> dfs = [&](int i, int j) -> bool{
+            if(i < 0 or j < 0 or i >= n or j >= m or visited[i][j] or !grid2[i][j])
                 return true;
 
-            if(!visited[i][j]) return false;
+            if(!grid1[i][j]) return false;
 
-            visited2[i][j] = true;
+            visited[i][j] = true;
 
             bool up, left, right, down;
             up = left = right = down = true;
 
-            up = dfs2(i-1, j);
-            left = dfs2(i, j-1);
-            down = dfs2(i+1, j);
-            right = dfs2(i, j+1);
+            up = dfs(i-1, j);
+            left = dfs(i, j-1);
+            down = dfs(i+1, j);
+            right = dfs(i, j+1);
 
             return up and left and down and right;
         };
@@ -54,9 +32,9 @@ class Solution {
         {
             for(int j = 0; j < m; ++j)
             {
-                if(!visited2[i][j] and grid2[i][j])
+                if(!visited[i][j] and grid2[i][j])
                 {
-                    if(dfs2(i, j))
+                    if(dfs(i, j))
                     {
                         ++subIsland;
                     }