Find if Path Exists in Graph

Create the adj list and then do DFS from the source node. If the path exists, it will eventually show up in the stack.

from collections import defaultdict

class Solution:
    def validPath(self, n: int, edges: List[List[int]], source: int, destination: int) -> bool:
        
        # create adj list then dfs
        adj = defaultdict(list)

        for u, v in edges:
            adj[u].append(v)
            adj[v].append(u)

        marked = set()
        stack = [source]
        marked.add(source)
        
        while stack:
            v = stack.pop()
            if v == destination:
                return True

            for w in adj[v]:
                if w not in marked:
                    stack.append(w)
                    marked.add(w)
        
        return False