[置顶] 最小生成树Prim算法

二话不说直接贴代码

原图传送门:http://www.tyut.edu.cn/kecheng1/site01/suanfayanshi/minispantree.asp

但是上面展现的是克鲁斯卡尔算法。我这里是普里姆算法。

#include <iostream>
#include <list>
#include <deque>
#include <algorithm>
using namespace std;

typedef struct Line
{
	int Dot1;
	int Dot2;
	int Power;
}Line;

static const int arr[] = {0,1,6,
	0,2,1,
	0,3,5,
	1,2,5,
	1,4,3,
	2,3,7,
	2,4,5,
	2,5,4,
	3,5,2,
	4,5,6
};

void BuildMap(list<Line>& vet)
{
	/*do
	{
	Line temp;
	cin>>temp.Dot1>>temp.Dot2>>temp.Power;
	vet.push_back(temp);
	}while(getchar() != '#');*/
	for(int i = 0;i < sizeof(arr)/(sizeof(int)*3);++i)
	{
		Line temp;
		temp.Dot1 = arr[i*3];
		temp.Dot2 = arr[i*3+1];
		temp.Power = arr[i*3+2];
		vet.push_back(temp);
	}
}

void MST(list<Line>&map,list<Line>& tree)
{
	list<Line *> Open;
	list<int>	OpenId;
	for(auto p = map.begin();p != map.end();++p)
	{
		Open.push_back(&*p);
		if(find(OpenId.begin(),OpenId.end(),p->Dot1) == OpenId.end())
			OpenId.push_back(p->Dot1);
		if(find(OpenId.begin(),OpenId.end(),p->Dot2) == OpenId.end())
			OpenId.push_back(p->Dot2);
	}
	Open.sort([](const Line* a,const Line* b){return a->Power < b->Power;});//支持C++11的编译器
	tree.push_back(**Open.begin());
	OpenId.erase(find(OpenId.begin(),OpenId.end(),(*Open.begin())->Dot1));
	OpenId.erase(find(OpenId.begin(),OpenId.end(),(*Open.begin())->Dot2));
	Open.pop_front();
	auto q = Open.begin();
	while(!OpenId.empty())
	{
		if(find(OpenId.begin(),OpenId.end(),(*q)->Dot1) == OpenId.end()
			&& find(OpenId.begin(),OpenId.end(),(*q)->Dot2) == OpenId.end())
		{//已加入
			Open.erase(q);
			q = Open.begin();
		}
		else if(find(OpenId.begin(),OpenId.end(),(*q)->Dot1) == OpenId.end()
			|| find(OpenId.begin(),OpenId.end(),(*q)->Dot2) == OpenId.end())
		{//已加入
			if(find(OpenId.begin(),OpenId.end(),(*q)->Dot1) == OpenId.end())
				OpenId.erase(find(OpenId.begin(),OpenId.end(),(*q)->Dot2));
			else if(find(OpenId.begin(),OpenId.end(),(*q)->Dot2) == OpenId.end())
				OpenId.erase(find(OpenId.begin(),OpenId.end(),(*q)->Dot1));
			tree.push_back(**q);
			Open.erase(q);
			q = Open.begin();
		}
		else
		{
			++q;
		}
	}
}

int main()
{
	list<Line> map;
	list<Line> tree;
	BuildMap(map);
	MST(map,tree);
	return 0;
}