Submission #198473

#	Time	Username	Problem	Language	Result	Execution time	Memory
198473		oolimry	Cheap flights (LMIO18_pigus_skrydziai)	C++14	28 / 100	2369 ms	127852 KiB

pigus_skrydziai

#include <bits/stdc++.h>

using namespace std;
typedef pair<long long,long long> ii; 
static vector<ii> adj[500005];
static vector<ii> tree[500005];
map<ii, long long> thonk;
class UFDS {
typedef vector<int> vi;
public:
    vi p, rak, setSize;
    int numSets;

    void create(int n){
        setSize.assign(n, 1);
        numSets = n;
        rak.assign(n, 0);
        p.assign(n, 0);
        for(int i =0;i < n;i++){
            p[i] = i;
        }
    }

    int findSet(int i){
        return (p[i] == i) ? i : (p[i] = findSet(p[i]));
    }

    bool isSameSet(int i, int j){
        return findSet(i) == findSet(j);
    }

    bool unionSet(int i, int j){
        if(isSameSet(i,j))
            return false;
        numSets--;
        int x = findSet(i);
        int y = findSet(j);

        if(rak[x] > rak[y]) {
            p[y] = x; setSize[x] += setSize[y];
        }

        else {
            p[x] = y; setSize[y] += setSize[x];
            if(rak[x] == rak[y]) rak[y]++;
        }
		return true;
    }
} uf;

struct edge{
	long long u;
	long long v;
	long long w;
};

bool comp(edge a, edge b){
	return a.w > b.w;
}
int main(){
	//freopen("i.txt","r",stdin);
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	long long n, m; cin >> n >> m;
	edge edges[m];
	
	uf.create(n);

	for(long long i = 0;i < m;i++){
		long long u, v; long long w;
		cin >> u >> v >> w; u--; v--;
		adj[u].push_back(ii(v,w));
		adj[v].push_back(ii(u,w));
		edges[i] = {u,v,w};
		thonk[ii(u,v)] = w;
		thonk[ii(v,u)] = w;
	}
	
	long long ans = 0;
	
	for(long long i = 0;i < n;i++){
		long long acc = 0;
		for(ii v : adj[i]) acc += v.second;
		ans = max(ans, acc);
	}
	
	sort(edges,edges+m,comp);
	
	for(edge e : edges){
		if(uf.unionSet(e.u, e.v)){
			tree[e.u].push_back(ii(e.v,e.w));
			tree[e.v].push_back(ii(e.u,e.w));
		}
	}
	
	if(n <= 200){
		for(int b = 0;b < n;b++){
			for(int c = 0;c < n;c++){
				if(thonk.find(ii(b,c)) == thonk.end()) thonk[ii(b,c)] = -1238213829038LL;
			}
		}
		for(int a = 0;a < n;a++){
			for(int b = 0;b < n;b++){
				for(int c = 0;c < n;c++){
					ans = max(ans, thonk[ii(a,b)] + thonk[ii(c,b)] + thonk[ii(a,c)]);
				}
			}
		}
	}
	
	for(long long i = 0;i < n;i++){
		if(tree[i].size() == 2){
			ii u = tree[i][0];
			ii v = tree[i][1];
			if(thonk.find(ii(u.first,v.first)) != thonk.end()){
				ans = max(ans, u.second + v.second + thonk[ii(u.first,v.first)]);
			}
		}
	}
	
	cout << ans;
}

• Subtask 1: 12 / 12
• Subtask 2: 0 / 25
• Subtask 3: 16 / 16
• Subtask 4: 0 / 47