added number of islands question

Author: Shrimadh

C++/number-of-islands.cpp

@@ -0,0 +1,41 @@
+class Solution {
+public:
+ bool visited[300][300];
+ int r[4] = {-1,0,0,1};
+ int c[4] = {0,-1,1,0};
+ bool val(int row,int col,vector<vector<char>>& grid,int M,int N)
+ {
+ return (row<M && col<N && row>=0 && col>=0 && !visited[row][col] && grid[row][col]=='1');
+ }
+ void dfs(int i,int j,vector<vector<char>>& grid, int M, int N)
+ {
+ visited[i][j] = true;
+ for(int a=0;a<4;a++)
+ {
+ int row = i + r[a];
+ int col = j + c[a];
+ if(val(row,col,grid,M,N))
+ {
+ dfs(row,col,grid,M,N);
+ }
+ }
+ }
+ int numIslands(vector<vector<char>>& grid) {
+ int m = grid.size();
+ int n = grid[0].size();
+ memset(visited,0,sizeof(visited));
+ int island_count = 0;
+ for(int i=0;i<m;i++)
+ {
+ for(int j=0;j<n;j++)
+ {
+ if(!visited[i][j] && grid[i][j]=='1')
+ {
+ dfs(i,j,grid,m,n);
+ island_count++;
+ }
+ }
+ }
+ return island_count;
+ }
+};

README.md

@@ -500,6 +500,7 @@ DISCLAIMER: This above mentioned resources have affiliate links, which means if
 | [Sachin_Upadhyay](https://github.com/sachsbu) <br> <img src="https://avatars.githubusercontent.com/u/24941685?v=4" width="100" height="100"> | India | Java | [GitHub](https://github.com/sachsbu) |
 | [Amisha Sahu](https://github.com/Amisha328) <br> <img src = "https://avatars.githubusercontent.com/u/58816552?v=4" width="100" height="100"> | India | C++ | [CodeChef](https://www.codechef.com/users/amisha328)<br/>[LeetCode](https://leetcode.com/Mishi328/)<br/>[HackerRank](https://www.hackerrank.com/amishasahu328)
 <br/>
+| [Shrimadh V Rao](https://github.com/Shrimadh) <br> <img src="https://avatars.githubusercontent.com/u/64469917?v=4" width="100" height="100"> | India | C++ | [GitHub](https://github.com/Shrimadh)
 <div align="right">
  <b><a href="#algorithms">⬆️ Back to Top</a></b>
 </div>