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;
}