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我想知道如何从节点 0(最小节点)开始获得 DAG 中的最长路径

我搜索了wiki并得到了以下算法:

algorithm dag-longest-path is
input: 
     Directed acyclic graph G
output: 
     Length of the longest path

length_to = array with |V(G)| elements of type int with default value 0

for each vertex v in topOrder(G) do
    for each edge (v, w) in E(G) do
        if length_to[w] <= length_to[v] + weight(G,(v,w)) then
            length_to[w] = length_to[v] + weight(G, (v,w))

return max(length_to[v] for v in V(G))

但是我不知道怎么实现,当然下面我写的代码是行不通的:(topo是拓扑排序的节点)

public static int longestPath(int[] topo){
    int[] dist = new int[topo.length];

    for(int i:topo){
        if(isArc(node,i)){
            if(dist[i]<dist[node]+1){
                dist[i] = dist[node] + 1;
            }
        }
    }
    return getMax(dist);
}

我应该怎么做?谢谢!

此外,你能给我一个算法来计算从 0 到 n-1 的不同路径的数量吗?

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