added number of islands program

CPP/Number of Islands.cpp

@@ -0,0 +1,75 @@
+//Given an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands.
+
+
+class Solution {
+ struct node{
+    int x;
+    int y;
+    node(int _x,int _y)
+    {
+        x=_x;
+        y=_y;
+    }
+};
+ public:
+  int visited[1000][1000];
+void bfs(int i,int j,int n,int m,vector<vector<char>>& grid)
+{
+    queue<node>q;
+    q.push(node(i,j));
+    visited[i][j]=1;
+    cout<<i<<" "<<j<<endl;
+    while(!q.empty())
+    {
+        int a=q.front().x;
+        int b=q.front().y;
+        q.pop();
+        cout<<a<<" "<<b<<endl;
+        int ar1[4]={1,0,-1,0};
+        int ar2[4]={0,-1,0,1};
+        for(int k=0;k<4;k++)
+        {
+            int c=a+ar1[k];
+            int d=b+ar2[k];
+
+            if(c>=0 && c<n && d>=0 && d<m && visited[c][d]==0)
+            {
+                visited[c][d]=1;
+                q.push(node(c,d));
+            }
+        }
+    }
+}
+int numIslands(vector<vector<char>>& grid) {
+   int n=grid.size();
+   int m=grid[0].size();
+
+    for(int i=0;i<n;i++)
+    {
+        for(int j=0;j<m;j++)
+        {
+            if(grid[i][j]=='1')
+            {
+                visited[i][j]=0;
+            }
+            else{
+                visited[i][j]=1;
+            }
+        }
+    }
+
+    int count=0;
+    for(int i=0;i<n;i++)
+    {
+        for(int j=0;j<m;j++)
+        {
+            if(grid[i][j]=='1' && visited[i][j]==0)
+            {
+              bfs(i,j,n,m,grid); 
+                count++;
+            }
+        }
+    }
+
+   return count; 
+}};