Submission #1105083

#	Time	Username	Problem	Language	Result	Execution time	Memory
1105083		InvMOD	Sjekira (COCI20_sjekira)	C++14	110 / 110	52 ms	11592 KiB

sjekira

#include<bits/stdc++.h>

using namespace std;

struct DSU{
    vector<int> par,sz,mx_val;
    DSU(int n, int t[]): par(n+1), sz(n+1), mx_val(n+1){
        for(int i = 1; i <= n; i++){
            par[i] = i;
            sz[i] = 1;
            mx_val[i] = t[i];
        }
        return;
    }

    int asc(int x){
        return x == par[x] ? x : par[x] = asc(par[x]);
    }

    bool join(int u, int v){
        u = asc(u), v = asc(v);
        if(u == v) return false;
        if(sz[u] < sz[v]) swap(u, v);
        par[v] = u;
        sz[u] += sz[v];
        mx_val[u] = max(mx_val[u], mx_val[v]);
        return true;
    }

    int weight(int u){
        return mx_val[asc(u)];
    }
};

using ll = long long;

const int N = 1e5+5;

int n, t[N], deg[N];
priority_queue<pair<int,int>> pq;
vector<int> adj[N];
vector<pair<int,int>> Edge;

void solve()
{
    cin >> n;
    for(int i = 1; i <= n; i++){
        cin >> t[i];
        pq.push(make_pair(t[i], i));
    }

    for(int i = 1; i < n; i++){
        int u,v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);

        ++deg[u], ++deg[v];
    }

    while(!pq.empty()){
        pair<int,int> e = pq.top(); pq.pop();

        int x = e.second, w = e.first;

        if(!deg[x]) continue;

        for(int v : adj[x]){
            if(deg[v]){
                Edge.push_back(make_pair(v, x));
                --deg[v], --deg[x];
            }
        }
    }
    reverse(Edge.begin(), Edge.end());

    DSU dsu(n, t);

    ll answer = 0;
    for(pair<int,int>& e : Edge){
        int u = e.first, v = e.second;
        answer = answer + 1ll * dsu.weight(u) + 1ll * dsu.weight(v);
        dsu.join(u, v);
    }
    cout << answer <<"\n";
}

int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    #define name "InvMOD"
    if(fopen(name".INP", "r")){
        freopen(name".INP", "r", stdin);
        freopen(name".OUT", "w", stdout);
    }

    solve();
    return 0;
}

Compilation message (stderr)

sjekira.cpp: In function 'void solve()':
sjekira.cpp:63:27: warning: unused variable 'w' [-Wunused-variable]
   63 |         int x = e.second, w = e.first;
      |                           ^
sjekira.cpp: In function 'int32_t main()':
sjekira.cpp:93:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |         freopen(name".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sjekira.cpp:94:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   94 |         freopen(name".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 30 / 30
• Subtask 4: 60 / 60