HDOJ 1102 Constructing Roads 最小生成树

//Prim算法

#include <iostream>

#include <memory.h>

#define INF 1000000

#define MAX 200

using namespace std;



int main()

{

	int arcs[MAX][MAX];

	bool isvisit[MAX];

	int min_weight[MAX];



	int N, Q;

	int x, y;

	freopen("C:\\Users\\Haojian\\Desktop\\test.txt", "r", stdin);

	while (cin >> N)

	{

		memset(isvisit, false, sizeof(isvisit));



		for (int i = 0; i < N; i++)

			for (int j = 0; j < N; j++)

				cin >> arcs[i][j];



		cin >> Q;



		for (int i = 0; i < Q; i++)

		{

			cin >> x >> y;

			arcs[x-1][y-1] = arcs[y-1][x-1] = 0;

		}



		for (int i = 0; i < N; i++)

			min_weight[i] = arcs[0][i];



		isvisit[0] = true;

		int _min, isallconnect;

		int hold, result = 0;

		for (int i = 1; i < N; i++)

		{

			_min = INF;

			isallconnect = true;

			for (int j = 0; j < N; j++)

			{

				if (!isvisit[j] && min_weight[j] < _min)

				{

					_min = min_weight[j];

					hold = j;



				}

			}	

			result += _min;



			isvisit[hold] = true;



			for (int j = 0; j < N; j++)

				if (!isvisit[j] && arcs[hold][j] < min_weight[j])

					min_weight[j] = arcs[hold][j];

		}



		cout << result << endl;

	}



	return 0;

}

 

 

//kruskal算法

#include <iostream>

#include <algorithm>

#define MAX 200

using namespace std;



int father[MAX];

int my_rank[MAX];



void make_set()

{

	for (int i = 0; i < MAX; i++)

	{

		father[i] = i;

		my_rank[i] = 0;

	}

}



int find_set(int x)

{

	if (x != father[x])

		father[x] = find_set(father[x]);



	return father[x];

}



void union_set(int x, int y)

{

	x = find_set(x);

	y = find_set(y);



	if (x == y) return;



	if (my_rank[x] > my_rank[y])

		father[y] = x;

	else

	{

		father[x] = y;



		if (my_rank[x] == my_rank[y])

			my_rank[y]++;

	}

}



struct edge

{

	int start;

	int end;

	int weight;

};



bool cmp(const edge& a, const edge& b)

{

	return a.weight < b.weight;

}



edge e[99*50+2];



int main()

{

	int N, Q, count;

	int x, y, cost;



	while (cin >> N)

	{

		count = 0;

		make_set();

		for (int i = 1; i <= N; i++)

		{

			for (int j = 1; j <= N; j++)

			{

				cin >> cost;

				if (j > i)

				{

					e[count].start = i;

					e[count].end = j;

					e[count++].weight = cost;

				}

			}

		}



		cin >> Q;



		for (int i = 0; i < Q; i++)

		{

			cin >> x >> y;

			x = find_set(x);

			y = find_set(y);



			if (x != y)

				union_set(x, y);

		}



		sort(e, e+count, cmp);

		N = count;

		count = 0;

		int sum = 0;

		while (count != N)

		{

			x = find_set(e[count].start);

			y = find_set(e[count].end);



			if (x != y)

			{

				union_set(x, y);

				sum += e[count].weight;

			}



			count++;

		}

		cout << sum << endl;

	}



	return 0;

}