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Copy pathCode03_TopologySort.java
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36 lines (33 loc) · 907 Bytes
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package class16;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
public class Code03_TopologySort {
// directed graph and no loop
public static List<Node> sortedTopology(Graph graph) {
// key 某个节点 value 剩余的入度
HashMap<Node, Integer> inMap = new HashMap<>();
// 只有剩余入度为0的点，才进入这个队列
Queue<Node> zeroInQueue = new LinkedList<>();
for (Node node : graph.nodes.values()) {
inMap.put(node, node.in);
if (node.in == 0) {
zeroInQueue.add(node);
}
}
List<Node> result = new ArrayList<>();
while (!zeroInQueue.isEmpty()) {
Node cur = zeroInQueue.poll();
result.add(cur);
for (Node next : cur.nexts) {
inMap.put(next, inMap.get(next) - 1);
if (inMap.get(next) == 0) {
zeroInQueue.add(next);
}
}
}
return result;
}
}