Cod sursa(job #2685491)

Utilizator SochuDarabaneanu Liviu Eugen Sochu Data 17 decembrie 2020 09:09:06
Problema Arbore partial de cost minim Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.57 kb
#include <bits/stdc++.h>
//#pragma GCC optimize ("03")
#define FastIO ios_base::sync_with_stdio(false) , cin.tie(0) , cout.tie(0)
#define FILES freopen("apm.in" , "r" , stdin) , freopen("apm.out" , "w" , stdout)
#define ll long long
#define ull unsigned long long
#define ld long double
#define eb emplace_back
#define pb push_back
#define qwerty1 first
#define qwerty2 second
#define qwerty3 -> first
#define qwerty4 -> second
#define umap unordered_map
#define uset unordered_set
#define pii pair < int , int >
#define pq priority_queue
#define dbg(x) cerr << #x << ": " << x << '\n'

namespace FastRead
{
    char buff[5000];int lg = 0 , p = 0;
    char nc()
    {
        if(lg == p){lg = fread(buff , 1 , 5000 , stdin);p = 0;if(!lg) return EOF;}
        return buff[p++];
    }
    template<class T>void read(T&x)
    {
        T sgn = 1; char c;while(!isdigit(c = nc()))if(c == '-')sgn = -1;
        x = c - '0';while(isdigit(c = nc()))x = x * 10 + c - '0';x *= sgn;
    }
}

using namespace FastRead;
using namespace std;

const int N = 4e5 + 10;
const int M = 1e9 + 7;
const ld PI = acos(-1);
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n , m , x , y , cost;
int root[N] , height[N];
vector < pii > answer;

struct ceva
{
    int cost , x , y;
}a[N];

bool inline cmp(ceva a , ceva b)
{
    return a.cost < b.cost;
}

int find(int x)
{
    int R;

    for(R = x ; R != root[R] ; R = root[R]);

    for( ; root[x] != x ; )
    {
        int aux = root[x];
        root[x] = R;
        x = aux;
    }
}

void unite(int rx , int ry)
{
    if(height[rx] < height[ry])
        root[rx] = ry;
    else if(height[rx] > height[ry])
        root[ry] = rx;
    else
    {
        ++height[ry];
        root[rx] = ry;
    }
}

signed main()
{
	#ifndef ONLINE_JUDGE
		FastIO , FILES;
	#endif

    int i;

    cin >> n >> m;

    for(i = 1 ; i <= m ; i++)
    {
        cin >> x >> y >> cost;
        a[i] = {cost , x , y};
    }

    sort(a + 1 , a + m + 1 , cmp);

    for(i = 1 ; i <= n ; i++)
    {
        root[i] = i;
        height[i] = 1;
    }

    int sum = 0;

    for(i = 1 ; i <= m ; i++)
    {
        int rx = find(a[i].x);
        int ry = find(a[i].y);

        if(rx != ry)
        {
            sum += a[i].cost;
            answer.pb({a[i].x , a[i].y});
            unite(rx , ry);
        }
    }

    cout << sum << '\n';
    cout << answer.size() << '\n';

    for(auto i : answer)
        cout << i.first << ' ' << i.second << '\n';

    return 0;
}