2021-1拓扑排序 c++

必要的准备

• 有向无环图才有拓扑排序。问题，如果判断一个有向图是否有环？点这里
• 拓扑排序的背后是约束关系，优先调度的问题首先被考虑。简单的，你应该先学习十进制数字再研究数论。问题，如何得到拓扑排序呢？点这里

拓扑排序API

• TopologicalSort(Digraph G) 构造函数
• bool isDAG() 是有向无环图么
• stack<int>* order()拓扑有序的节点

代码

#pragma once
#include"DirectedCycle.h"
#include"DepthFirstOrder.h"

class TopologicalSort
{
    
    
public:
	TopologicalSort(Digraph& G);

	bool isDAG() {
    
     return !m_order->empty(); }
	stack<int>* order() {
    
     return m_order; }
private:
	stack<int>* m_order=nullptr;
};

void testTopSort();

#include "TopologicalSort.h"

TopologicalSort::TopologicalSort(Digraph& G)
{
    
    
	DirectedCycle cycleFinder(G);
	if (!cycleFinder.hasCycle()) {
    
    
		DepthFirstOrder* dfO=new DepthFirstOrder(G);
		m_order=dfO->getRePost();
	}
}

void testTopSort() {
    
    
	Digraph G("tinyDAG.txt");
	TopologicalSort topS(G);
	out(topS.isDAG()), hh;
	stack<int>* stk = topS.order();
	while (!stk->empty()) {
    
    
		int x = stk->top();
		out(x);
		stk->pop();
	}
	hh;
}

tinyDAG.txt

13
15
2 3 
0 6 
0 1 
2 0 
11 12  
9 12  
9 10  
9 11 
3 5 
8 7 
5 4 
0 5 
6 4 
6 9 
7 6

另一种思路 基于队列的拓扑排序