IBgraph1

public class Solution {
    public int solve(int A, int[][] B) {
        ArrayList<Integer>[] graph = new ArrayList[A+1]; //A+1 because vertex are from 1 to A
        for(int i=0;i<=A;i++){ //make graph
            graph[i] = new ArrayList<>();
        }
        for(int i=0;i<B.length;i++){
            int v1 = B[i][0];
            int v2 = B[i][1];
            graph[v1].add(v2);
        }
        boolean visited[] = new boolean[A+1];
        
        boolean ans = dfs(graph,1,A,visited); //apply dfs

        return ans ? 1 : 0;
    }
    public boolean dfs(ArrayList<Integer>[] graph, int src, int target, boolean visited[]){ //apply simple dfs to check if equal
        if(src == target) return true;
        visited[src] = true;
        for(Integer nbr : graph[src]){
            if(visited[nbr] == false){
                boolean ans = dfs(graph,nbr,target,visited);
                if(ans) return true;
            }
        }
        return false;
    }
}