Tarjan算法实现，低值节点问题

Question

我正试图在图中的一组节点上执行tarjans算法，我可以成功地找到强连接组件，但根或低值节点总是关闭的，即使对于只有1个元素的SCC，根节点也与该元素不匹配例如：

0-3 IS LOW VALUE NODE
[82-97]
529-529 IS LOW VALUE NODE
[69-81]
379-379 IS LOW VALUE NODE
[57-68]
1619-1619 IS LOW VALUE NODE
[136-137]
415-415 IS LOW VALUE NODE
[45-56]

其中顶部是低值节点，底部是组成SCC 的1元素

我目前拥有的代码在这里

package Structs;
import java.util.*;
public class TarjanSCC {
private int id;
private boolean[] onStack;
private int[] ids, low;
private Deque<Integer> stack;
private Graph<BasicBlock> graph;
private Map<BasicBlock, Integer> nodeMap;
private BasicBlock[] nodes;
private static final int UNVISITED = -1;
public TarjanSCC(Graph<BasicBlock> graph) {
this.graph = graph;
}
public void runTSCC() {
runTSCC(graph);
}
public void runTSCC(Graph<BasicBlock> nodeGraph) {
//Initialize values for sorting
this.nodes = nodeGraph.getNodes().toArray(new BasicBlock[nodeGraph.size()]);
int size = nodes.length;
this.ids = new int[size];
this.low = new int[size];
this.onStack = new boolean[size];
this.stack = new ArrayDeque<>();
this.nodeMap = new HashMap<>();
//Mark all nodes as unused, place nodes in a map so index is easily retrievable from node
for(int i = 0; i < size; i++) {
nodeMap.put(nodes[i], i);
ids[i] = UNVISITED;
}
//Invoke the DFS algorithm on each unvisited node
for(int i = 0; i < size; i++) {
if (ids[i] == UNVISITED) dfs(i, nodeGraph);
}
}
private void dfs(int at, Graph<BasicBlock> nodeGraph) {
ids[at] = low[at] = id++;
stack.push(at);
onStack[at] = true;
//Visit All Neighbours of graph and mark as visited and add to stack,
for (BasicBlock edge : nodeGraph.getEdges(nodes[at])) {
int nodeArrayIndex = nodeMap.get(edge);
if (ids[nodeArrayIndex] == UNVISITED) {
dfs(nodeArrayIndex, nodeGraph);
low[at] = Math.min(low[at], low[nodeArrayIndex]);
}
else if (onStack[nodeArrayIndex]) low[at] = Math.min(low[at], nodeArrayIndex);
}
//We've visited all the neighours, lets start emptying the stack until we're at the start of the SCC
if (low[at] == ids[at]) {
List<BasicBlock> sccList = new ArrayList<>();
for (int node = stack.pop();; node = stack.pop()) {
onStack[node] = false;
sccList.add(0, nodes[node]);
if (node == at) {
System.out.println(nodes[low[at]] + " IS LOW VALUE NODE");
System.out.println(sccList);
break;
}
}
}
}
}

我怀疑问题在于设置低值。我不认为需要任何其他类信息，因为从图中检索边没有问题

Answer 1

我索引了根节点错误的节点[at]是访问根节点的正确方法