LeetCode 797 All Paths From Source to Target

最新推荐文章于 2021-08-25 19:52:38 发布

原创最新推荐文章于 2021-08-25 19:52:38 发布 · 334 阅读

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本文介绍了一种在有向无环图中查找从节点0到节点N-1的所有可能路径的方法，并提供了一个C++实现的例子。该算法使用深度优先搜索（DFS）策略，递归地探索所有可能的路径。

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Given a directed, acyclic graph of N nodes. Find all possible paths from node 0 to node N-1, and return them in any order.

The graph is given as follows: the nodes are 0, 1, …, graph.length - 1. graph[i] is a list of all nodes j for which the edge (i, j) exists.

Example:
Input: [[1,2], [3], [3], []] 
Output: [[0,1,3],[0,2,3]] 
Explanation: The graph looks like this:
0--->1
|    |
v    v
2--->3
There are two paths: 0 -> 1 -> 3 and 0 -> 2 -> 3.

Note:

The number of nodes in the graph will be in the range [2, 15].
You can print different paths in any order, but you should keep the order of nodes inside one path.

解题思路

深搜

代码

class Solution {
public:
    vector<vector<int>> paths;

    void findPath(vector<vector<int>> &graph, vector<int> path, int x, int target) {
        if (x == target)
            paths.emplace_back(path);
        for (auto each: graph[x]) {
            auto tmp = path;
            tmp.push_back(each);
            findPath(graph, tmp, each, target);
        }
    }

    vector<vector<int>> allPathsSourceTarget(vector<vector<int>> &graph) {
        paths.clear();
        int N = (int) graph.size();
        findPath(graph, vector<int>{0}, 0, N - 1);
        return paths;
    }
};