Q1 Find if Path Exists in Graph - LeetCode 1971

PHOTO

Sat Apr 08 2023 16:05:43 GMT+0000 (Coordinated Universal Time)

Saved by @Ayush_dabas07

class Solution {
    public boolean validPath(int n, int[][] edges, int source, int destination) {
        //make HM for vertices and edges
        HashMap<Integer,ArrayList<Integer>> graph = new HashMap<>();

        for(int edge[] : edges){
            int a = edge[0] , b = edge[1];
            
            graph.computeIfAbsent(a , k -> new ArrayList<>()).add(b);
            graph.computeIfAbsent(b , k -> new ArrayList<>()).add(a);
        }

        //to prevent infinite loop between neighours
        boolean[] visited = new boolean[n];

        return dfs(graph , source , destination , visited);
    }

    //recursive  DFS
    public boolean dfs(HashMap<Integer,ArrayList<Integer>> graph,int source , 
    int destination , boolean visited[]){

        if(source == destination)
        return true;
        
        //mark the source first
        visited[source] = true;

        for(int edge : graph.get(source)){
            
            if(visited[edge] == false){

                if(dfs(graph , edge , destination , visited))
                return true;
            }
        }

        return false;
    }
}

https://leetcode.com/problems/find-if-path-exists-in-graph/

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