【Kruskal 和 Prim】

图是这样的
图片来源：
添加链接描述

#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
#include <queue>
using namespace std;

struct edge {
	edge() {}
	edge(char s, char e, int w) :start(s), end(e), weight(w) {}
	bool operator<(edge x1) {
		return weight < x1.weight;
	}
	char start, end;
	int weight;
};


class Graph
{
public:
	char Find_Set(char c);
	void Union(char c1, char c2);
	void Kruskal();
	void Prim(char C);

	vector<edge> Kruskal_result;
	vector<edge> Kruskal_edge;
	map<char, char> Kruskal_vertex;
	map<char, pair<char,int>> Prim_result;
	map<char, vector<pair<char, int>>> Prim_edge;;
	map<char, pair<int, int>> Prim_vertex;	//key	visited		weight
};

char Graph::Find_Set(char c)
{
	char p = Kruskal_vertex[c];
	while (p != Kruskal_vertex[p])
		p = Kruskal_vertex[p];
	
	return p;
}

void Graph::Union(char c1, char c2)
{
	char t1 = Find_Set(c1);
	char t2 = Find_Set(c2);
	Kruskal_vertex[t2] = t1;
}

void Graph::Kruskal()
{
	for (vector<edge>::iterator i = Kruskal_edge.begin(); i != Kruskal_edge.end(); i++) {
		if (Find_Set((*i).start) != Find_Set((*i).end)) {
			Kruskal_result.push_back((*i));
			Union((*i).start, (*i).end);
		}
	}
}

void Graph::Prim(char C)		//起点
{
	map<char, int> Q;
	
	Prim_vertex[C].first = 1;	//visited
	Prim_vertex[C].second = 0;	//dist = 0
	Prim_result[C].first = C;

	for (map<char, pair<int, int>>::iterator i = Prim_vertex.begin(); i != Prim_vertex.end(); i++) {
		Q[(*i).first] = (*i).second.second;
	}

	while (!Q.empty()){
		char temp;
		int value = INT_MAX;
		for (map<char, int>::iterator i = Q.begin(); i != Q.end(); i++) {
			if (value > (*i).second) {
				temp = (*i).first;
				value = (*i).second;
			}
			
		}
		map<char, int>::iterator E = Q.find(temp);
		Q.erase(E);
		Prim_vertex[temp].first = 1;

		int size = Prim_edge[temp].size();
		for (int i = 0; i < size; i++) {
			if (!Prim_vertex[Prim_edge[temp][i].first].first && Prim_vertex[Prim_edge[temp][i].first].second > Prim_edge[temp][i].second){
				Prim_vertex[Prim_edge[temp][i].first].second = Prim_edge[temp][i].second;
				Q[Prim_edge[temp][i].first] = Prim_edge[temp][i].second;
				Prim_result[Prim_edge[temp][i].first].first = temp;
				Prim_result[Prim_edge[temp][i].first].second = Prim_edge[temp][i].second;
			}
		}
	}
}

int main()
{
	Graph G;
	int n, m, weight;
	char c, start, end;
	cin >> n >> m;
	while (n--) {
		cin >> c;
		G.Kruskal_vertex[c] = c;
		G.Prim_vertex[c].first = 0;				//visited
		G.Prim_vertex[c].second = INT_MAX;		//dist
	}
	while (m--) {
		cin >> start >> end >> weight;
		G.Kruskal_edge.push_back(edge(start, end, weight));
		G.Prim_edge[start].push_back(make_pair(end, weight));
		G.Prim_edge[end].push_back(make_pair(start, weight));
	}
	

	sort(G.Kruskal_edge.begin(), G.Kruskal_edge.end());

	G.Kruskal();
	cout << endl << endl;

	int size = G.Kruskal_result.size();
	cout << "Kruskal:" << endl;
	for (int i = 0; i < size; i++)
		cout << G.Kruskal_result[i].start << ' ' << G.Kruskal_result[i].end << ' ' << G.Kruskal_result[i].weight << endl;
	cout << endl << endl;

	start = 'a';
	G.Prim(start);
	cout << "Prim:" << endl;
	for (map<char, pair<char, int>>::iterator i = G.Prim_result.begin(); i != G.Prim_result.end(); i++) {
		if ((*i).first == start) continue;
		cout << (*i).first << ' ' << (*i).second.first << ' ' << (*i).second.second << endl;
	}
	cout << endl << endl;
}

标签：Prim,temp,Kruskal,vertex,edge,first
来源： https://blog.csdn.net/m0_52106197/article/details/122284919