Constructing Roads最小生成树

Constructing Roads
原题链接https://vjudge.net/contest/352170#problem/C


题目给出所有路的关系，以及已经被修好的路，求修剩下的路的最小值。
地图已经给出 直接读取就好，在读取已经修好的路的时候，将已经修好的路的权值改为0即可，正常进行计算，
Prim：

#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
#include <queue>
using namespace std;
const int INF = 0x3f3f3f3f;
long long map[305][305];
long long dis[300005];
bool vis[300005];
long long ans;
long long n;
void prim()
{
    ans = 0;
    long long i, j;
    for (i = 1; i <= n; i++)
    {
        dis[i] = map[1][i];
        vis[i] = false;
    }
    vis[1] = true;
    for (i = 0; i < n - 1; i++)
    {
        long long minn = INF;
        long long p = 1;
        for (j = 1; j <= n; j++)
        {
            if (!vis[j] && dis[j] < minn)
            {
                minn = dis[j];
                p = j;
            }
        }
        // cout << "***" << endl;
        //  for (j = 1; j <= n; j++)
        //  {
        //      cout << dis[j] << " ";
        //   }
        //    cout << endl;
        if (minn == INF)
        {
            ans = -1;
            return;
        }
        ans += minn;
        vis[p] = true;
        for (j = 1; j <= n; j++)
        {
            if (!vis[j] && dis[j] > map[p][j])
            {
                dis[j] = map[p][j];
            }
        }
    }
    return;
}
int main()
{
    long long i, j;
    scanf("%lld", &n);
    for (i = 0; i <= n; i++)
    {
        for (j = 0; j <= n; j++)
        {
            map[i][j] = INF;
        }
    }
    for (i = 1; i <= n; i++)
    {
        for (j = 1; j <= n; j++)
        {
            scanf("%lld", &map[i][j]);
            //   if (i == j)
            //  {
            //      map[i][j] = INF;
            // }
        }
    }

    long long m;
    scanf("%lld", &m);
    while (m--)
    {
        long long a, b;
        scanf("%lld %lld", &a, &b);//读取已经被连接的路。
        map[a][b] = 0;
        map[b][a] = 0;
    }
    // for (i = 1; i <= n; i++)
    // {
    //for (j = 1; j <= n; j++)
    //{
    //     printf("%5lld ", map[i][j]);
    ///   }
    //     cout << endl;
    //   }
    prim();
    cout << ans << endl;
    return 0;
}

Kruskal:

#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
#include <queue>
using namespace std;
long long pre[300005];
long long map[3005][3005];
struct node
{
	long long u;
	long long v;
	long long w;
} stu[300005];
long long ans;
long long cnt;
bool cmp(node x, node y)
{
	return x.w < y.w;
}
long long find(long long x)
{
	if (x == pre[x])
	{
		return x;
	}
	return pre[x] = find(pre[x]);
}
void join(long long x, long long y, long long w)
{
	long long ss1 = find(x);
	long long ss2 = find(y);
	if (ss1 != ss2)
	{
		pre[ss2] = ss1;
		ans += w;
		cnt--;
	}
}
int main()
{
	long long n, i;
	scanf("%lld", &n);
	ans = 0;
	cnt = n;
	long long m, j;
	for (i = 0; i <= n; i++)
	{
		pre[i] = i;
	}
	for (i = 1; i <= n; i++)
	{
		for (j = 1; j <= n; j++)
		{
			scanf("%lld", &map[i][j]);
		}
	}
	long long t, a, b;
	scanf("%lld", &t);
	while (t--) //将已经修好的路长度清零,直接连接起来。
	{
		scanf("%lld %lld", &a, &b);
		join(a, b, 0);
		map[a][b] = 0;
		map[b][a] = 0;
	}
	long long k = 0;
	for (i = 1; i <= n; i++)
	{
		for (j = i + 1; j <= n; j++)
		{
			stu[k].u = i;
			stu[k].v = j;
			stu[k].w = map[i][j];
			k++;
		}
	}
	sort(stu, stu + k, cmp);
/*	for (i = 0; i < k; i++)
	{
		printf("*%lld %lld %lld\n", stu[i].u, stu[i].v, stu[i].w);
	}
	for (i = 0; i <= n;i++)
	{
		cout << pre[i] << endl;
	}
		cout << endl;*/
	for (i = 0; i < k; i++)
	{
		join(stu[i].u, stu[i].v, stu[i].w);
		if (cnt == 1)
		{
			break;
		}
	}
	if (cnt > 1)
	{
		ans = -1;
	}
	cout << ans << endl;
	return 0;
}