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package class16;
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import java.util.ArrayList;
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import java.util.Comparator;
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import java.util.HashMap;
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// OJ链接：https://www.lintcode.com/problem/topological-sorting
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public class Code03_TopologicalOrderDFS1 {
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// 不要提交这个类
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public static class DirectedGraphNode {
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public int label;
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public ArrayList<DirectedGraphNode> neighbors;
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public DirectedGraphNode(int x) {
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label = x;
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neighbors = new ArrayList<DirectedGraphNode>();
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}
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}
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// 提交下面的
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public static class Record {
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public DirectedGraphNode node;
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public int deep;
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public Record(DirectedGraphNode n, int o) {
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node = n;
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deep = o;
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}
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}
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public static class MyComparator implements Comparator<Record> {
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@Override
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public int compare(Record o1, Record o2) {
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return o2.deep - o1.deep;
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}
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}
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public static ArrayList<DirectedGraphNode> topSort(ArrayList<DirectedGraphNode> graph) {
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HashMap<DirectedGraphNode, Record> order = new HashMap<>();
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for (DirectedGraphNode cur : graph) {
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f(cur, order);
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}
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ArrayList<Record> recordArr = new ArrayList<>();
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for (Record r : order.values()) {
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recordArr.add(r);
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}
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recordArr.sort(new MyComparator());
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ArrayList<DirectedGraphNode> ans = new ArrayList<DirectedGraphNode>();
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for (Record r : recordArr) {
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ans.add(r.node);
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}
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return ans;
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}
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public static Record f(DirectedGraphNode cur, HashMap<DirectedGraphNode, Record> order) {
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if (order.containsKey(cur)) {
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return order.get(cur);
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}
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int follow = 0;
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for (DirectedGraphNode next : cur.neighbors) {
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follow = Math.max(follow, f(next, order).deep);
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}
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Record ans = new Record(cur, follow + 1);
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order.put(cur, ans);
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return ans;
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}
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}
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