Path in Directed Graph

 https://www.interviewbit.com/old/problems/path-in-directed-graph/

bool dfs(vector<vector<int>> &adj, vector<bool> &visited, int start, int dest){
    visited[start] = true;
    if(start == dest) return true;
    for(int i = 0; i<adj[start].size(); i++){
        if(!visited[adj[start][i]]){
            if(dfs(adj, visited, adj[start][i], dest)) return true;
        }
        // return dfs(adj, visited, adj[start][i], dest); -> this is bad
        // if recursion is exhausting the call stack (big input case) instead of
        // sending the "true" thru the call stack, just check if iteration returns true and
        // return true to main fun.
    }
    return false;
}

int Solution::solve(int A, vector<vector<int>> &B) {
    vector<vector<int>> adj(A+1);
    for(int i = 0; i<B.size(); i++){
        adj[B[i][0]].push_back(B[i][1]); // directed graph
    }
    vector<bool> visited(A+1, false);
    return dfs(adj, visited, 1, A);
}