使用深度优先搜索查找路径

public class DepthFirstPaths {

    private int s;
    private boolean[] marked;
    private int[] edgeTo;

    public DepthFirstPaths(Graph G, int s) {
        this.s = s;
        marked = new boolean[G.V()];
        edgeTo = new int[G.V()];
        dfs(G, s);
    }

    private void dfs(Graph G, int v) {
        marked[v] = true;
        for (int w:G.adj(v)) {
            if (!marked[w]) {
                edgeTo[w] = v;
                dfs(G, w);
            }
        }
    }

    public boolean hasPathTo(int v) {
        return marked[v];
    }


    public Iterable<Integer> pathTo(int v) {
        if (!marked[v]) return null;
        Stack<Integer> path = new Stack<>();
        for (int x = v; x != s; x = edgeTo[x])
            path.push(x);
        path.push(s);
        return path;
    }

}