Merge pull request #162 from shivamsingh67/patch-3

Create Number of Islands.cpp

Author: gantavyamalviya

Dynamic Programming/Number of Islands.cpp

@@ -0,0 +1,43 @@
+class Solution {
+public:
+
+bool Isvisit(int i,int j,int n,int m, vector<vector<char>>&grid){
+    if(i >= 0 && i < n && j >= 0 && j < m && grid[i][j] == '1'){
+        return true;
+    }
+    return false;
+}
+
+void dfs(int i,int j,int n,int m, vector<vector<char>>&grid){
+    grid[i][j] = '0';
+
+    if(Isvisit(i+1,j,n,m,grid)){
+        dfs(i+1,j,n,m,grid);
+    }
+    if(Isvisit(i-1,j,n,m,grid)){
+        dfs(i-1,j,n,m,grid);
+    }
+    if(Isvisit(i,j+1,n,m,grid)){
+        dfs(i,j+1,n,m,grid);
+    }
+    if(Isvisit(i,j-1,n,m,grid)){
+        dfs(i,j-1,n,m,grid);
+    }
+}
+
+    int numIslands(vector<vector<char>>& grid) {
+        int n = grid.size();
+        int m = grid[0].size();
+        int cnt = 0;
+
+        for(int i = 0; i < n; i++){
+            for(int j = 0; j < m; j++){
+                if(grid[i][j] == '1'){
+                    dfs(i,j,n,m,grid);
+                    cnt++;
+                }
+            }
+        }
+        return cnt;
+    }
+};