Islands.txt

Islands
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An island is a small piece of land surrounded by water . A group of islands is said to be connected if we can reach from any given island to any other island in the same group . Given V islands (numbered from 1 to V) and E connections or edges between islands. Can you count the number of connected groups of islands.
Input Format :
The first line of input contains two integers, that denote the value of V and E.
Each of the following E lines contains two integers, that denote that there exists an edge between vertex a and b. 
Output Format :
Print the count the number of connected groups of islands
Constraints :
0 <= V <= 1000
0 <= E <= (V * (V-1)) / 2
0 <= a <= V - 1
0 <= b <= V - 1
Time Limit: 1 second
Sample Input 1:
5 8
0 1
0 4
1 2
2 0
2 4
3 0
3 2
4 3
Sample Output 1:
1 

Solution://///////
public class Solution {
    
      public static void helpDFS(int edges[][],boolean visited[],int start, int n){  
       //mark visited as true   
        visited[start]=true; 
        //go through all the adjacent vertices of start vertex which have value 1 in the adjacency matrix  
          for(int j=0;j<n;j++){
              if(edges[start][j]==1&&!visited[j]){
                 helpDFS(edges,visited,j,n); 
              }
          }
    }

	public static int numConnected(int[][] edges, int n) {
        
		boolean[] visited = new boolean[n];
        int count = 0;
		for(int i=0;i<n;i++){
          //if the vertex is not visted call dfs on the vertex  
          if(!visited[i]){
             //after 1st call mark count = count+1; 
             count++;
             helpDFS(edges,visited,i,n);
            
          }
        }
        return count; //this returns the final number of times helpDFS was called, that is number of coonected components/islands
        
    }
}