[LeetCode] Easy - 1971 Find if Path Exists in Graph

▶1971 - Find if Path Exists in Graph

▶문제

There is a bi-directional graph with n vertices, where each vertex is labeled from 0 to n - 1 (inclusive). The edges in the graph are represented as a 2D integer array edges, where each edges[i] = [ui, vi] denotes a bi-directional edge between vertex ui and vertex vi. Every vertex pair is connected by at most one edge, and no vertex has an edge to itself.

You want to determine if there is a valid path that exists from vertex source to vertex destination.

Given edges and the integers n, source, and destination, return true if there is a valid path from source to destination, or false otherwise.

 

▶예제

Input: n = 3, edges = [[0,1],[1,2],[2,0]], source = 0, destination = 2
Output: true
Explanation: There are two paths from vertex 0 to vertex 2:
- 0 → 1 → 2
- 0 → 2

Input: n = 6, edges = [[0,1],[0,2],[3,5],[5,4],[4,3]], source = 0, destination = 5
Output: false
Explanation: There is no path from vertex 0 to vertex 5.

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▶풀이

처음에 union find문제인 줄 알고 풀었다가 시간 초과가 났다.

그래서 그냥 단순하게 경로를 찾는 BFS로 풀었는데, 통과가 됐다.

class Solution:
    def validPath(self, n: int, edges: List[List[int]], source: int, destination: int) -> bool:
        q = deque([source])
        visit = [0 for i in range(n)]
        nei = defaultdict(list)

        for n1, n2 in edges:
            nei[n1].append(n2)
            nei[n2].append(n1)

        while q:
            node = q.popleft()
            if node == destination:
                return True
            
            for n in nei[node]:
                if visit[n] == 0:
                    visit[n] = 1
                    q.append(n)
        
        return False