Commit

Author: rachitvk

Leetcode/MaxAreaofIsland.cpp

@@ -0,0 +1,43 @@
+class Solution {
+
+public:
+    
+    int ans=0;
+    int c=0;
+    int visited[1000][1000]={0};
+    
+    bool issafe(int p,int q,vector<vector<int>>& grid){
+        return (p>=0 && p<grid.size() && q>=0 && q<grid[0].size());
+    }
+    
+    void dfs(int u,int v,vector<vector<int>>& grid){
+        
+         visited[u][v]=1;
+         int a[]={0,0,1,-1};
+         int b[]={1,-1,0,0};
+         c++;
+        
+        for(int i=0;i<4;i++){
+            int p=u+a[i];int q=v+b[i];
+            
+            if(issafe(p,q,grid) && visited[p][q]==0 && grid[p][q]==1){
+                dfs(p,q,grid);
+            }
+        }
+    }
+    
+    int maxAreaOfIsland(vector<vector<int>>& grid) {
+        
+        for(int i=0;i<grid.size();i++){
+            for(int j=0;j<grid[0].size();j++){
+                if(!visited[i][j] && grid[i][j]==1){
+                    c=0;
+                    dfs(i,j,grid);
+                    ans=max(ans,c);
+                }
+            }
+        }
+        
+        return ans;
+    }
+};

Leetcode/NumberofIslands.cpp

@@ -0,0 +1,38 @@
+class Solution {
+public:
+    
+    int ans=0;
+    int visited[1000][1000]={0};
+    
+    bool issafe(int p,int q,vector<vector<char>>& grid){
+        return (p>=0 && p<grid.size() && q>=0 && q<grid[0].size());
+    }
+    
+    void dfs(int u,int v,vector<vector<char>>& grid){
+        
+         visited[u][v]=1;
+         int a[]={0,0,1,-1};
+         int b[]={1,-1,0,0};
+        
+        for(int i=0;i<4;i++){
+            int p=u+a[i];int q=v+b[i];
+            
+            if(issafe(p,q,grid) && visited[p][q]==0 && grid[p][q]=='1'){
+                dfs(p,q,grid);
+            }
+        }
+    }
+    
+    int numIslands(vector<vector<char>>& grid) {
+        for(int i=0;i<grid.size();i++){
+            for(int j=0;j<grid[0].size();j++){
+                if(!visited[i][j] && grid[i][j]=='1'){
+                    ans++;
+                    dfs(i,j,grid);
+                }
+            }
+        }
+        
+        return ans;
+    }
+};

Leetcode/SurroundedRegions.cpp

@@ -0,0 +1,67 @@
+class Solution {
+public:
+    
+    int ans=0;
+    int visited[1000][1000]={0};
+    
+    bool issafe(int p,int q,vector<vector<char>>& grid){
+        return (p>=0 && p<grid.size() && q>=0 && q<grid[0].size());
+    }
+    
+    void dfs(int u,int v,vector<vector<char>>& grid){
+        
+         visited[u][v]=1;
+         grid[u][v]='F';
+         int a[]={0,0,1,-1};
+         int b[]={1,-1,0,0};
+        
+        for(int i=0;i<4;i++){
+            int p=u+a[i];int q=v+b[i];
+            
+            if(issafe(p,q,grid) && visited[p][q]==0 && grid[p][q]=='O'){
+                dfs(p,q,grid);
+            }
+        }
+    }
+    
+    void solve(vector<vector<char>>& board) {
+        
+        
+        int r=board.size();
+        if(r==0)
+            return;
+        int c=board[0].size();
+        
+        
+        for(int i=0;i<c;i++){
+            if(!visited[0][i] && board[0][i]=='O')
+                dfs(0,i,board);
+        }
+        
+        for(int i=0;i<c;i++){
+            if(!visited[r-1][i] && board[r-1][i]=='O')
+                dfs(r-1,i,board);
+        }
+        
+        for(int i=0;i<r;i++){
+            if(!visited[i][0] && board[i][0]=='O')
+                dfs(i,0,board);
+        }
+        
+        for(int i=0;i<r;i++){
+            if(!visited[i][c-1] && board[i][c-1]=='O')
+                dfs(i,c-1,board);
+        }
+        
+        for(int i=0;i<board.size();i++){
+            for(int j=0;j<board[0].size();j++){
+                if(board[i][j]=='O')
+                    board[i][j]='X';
+                else if(board[i][j]=='F')
+                    board[i][j]='O';
+            }
+        }
+          
+    }   
+    
+};