Submission #1034782

#	Time	Username	Problem	Language	Result	Execution time	Memory
1034782		_8_8_	Road Closures (APIO21_roads)	C++17	24 / 100	2062 ms	33340 KiB

roads

#include "roads.h"

#include <vector>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = (int)1e5 +12;
vector<pair<int,int>> g[maxn];
ll dp[maxn][2];
int k;
int dep[maxn];
vector<ll> pref[maxn],pref1[maxn];
void prec(int v,int pr = -1,int _w = 0) {
    for(auto [to,w]:g[v]) {
        if(to == pr) continue;
        dep[to] = dep[v] + 1;
        prec(to,v,w);
        pref[v].push_back(w);
        pref1[v].push_back(w);
    }
    if(pr != -1){
        pref1[v].push_back(_w);
    }
    sort(pref[v].rbegin(),pref[v].rend());
    for(int i = 1;i < (int)pref[v].size();i++) {
        pref[v][i] += pref[v][i - 1];
    }
    sort(pref1[v].rbegin(),pref1[v].rend());
    for(int i = 1;i < (int)pref1[v].size();i++) {
        pref1[v][i] += pref1[v][i - 1];
    }
}
int vis[maxn],timer = 0;
void dfs(int v,int pr = -1){
    vis[v] = timer;
    if(g[v].empty() || (int)g[g[v][0].first].size() > k) {
        ll S = 0;
        vector<ll> can;
        for(auto [to,w]:g[v]) {
            if(to == pr) continue;
            if((int)g[to].size() > k) {
                dfs(to,v);
            }else {
                dp[to][0] = dp[to][1] = 0;
            }
            S += dp[to][0] + w;
            can.push_back(dp[to][1] - (dp[to][0] + w));
        }
        sort(can.begin(),can.end());
        dp[v][0] = dp[v][1] = S;
        for(int i = 0;i < (int)can.size() && can[i] < 0;i++){
            if(i < k){
                dp[v][0] += can[i];
            }
            if(i < k - 1)
            {
                dp[v][1] += can[i];
            }
        }
    }else{
        if(pr == -1){
            if(pref1[v].empty()){
                dp[v][0] = dp[v][1] = 0;
                return;
            }
            dp[v][0] = dp[v][1] = pref1[v].back();
            if(k - 1 >= (int)pref1[v].size()){
                dp[v][0] = 0;
            }else{
                dp[v][0] -= pref1[v][k - 1];
            }
            if(k - 2 >= (int)pref1[v].size()){
                dp[v][1] = 0;
            }else{
                dp[v][1] -= pref1[v][k - 2];
            }
        }else {
            if(pref[v].empty()){
                dp[v][0] = dp[v][1] = 0;
                return;
            }
            dp[v][0] = dp[v][1] = pref[v].back();
            if(k - 1 >= (int)pref[v].size()){
                dp[v][0] = 0;
            }else{
                dp[v][0] -= pref[v][k - 1];
            }
            if(k - 2 >= (int)pref[v].size()){
                dp[v][1] = 0;
            }else{
                dp[v][1] -= pref[v][k - 2];
            }
        }
    }
}
vector<long long> minimum_closure_costs(int N,vector<int> U,vector<int> V,vector<int> W) {
    for(int i = 0;i < N - 1;i++){
        g[U[i]].emplace_back(V[i],W[i]);
        g[V[i]].emplace_back(U[i],W[i]);
    }
    for(int i = 0;i < N;i++) {
        sort(g[i].begin(),g[i].end(),[&](pair<int,int> x,pair<int,int> y) {
            return ((int)g[x.first].size()) > (int)g[y.first].size();
        });
    }
    vector<ll> res;
    prec(0);
    vector<int> P(N);
    iota(P.begin(),P.end(),0);
    sort(P.begin(),P.end(),[&](int x,int y){
        return dep[x] < dep[y];
    });
    for(int i = 0;i < N;i++) {
        ll ss = 0;
        ++timer;
        k = i;
        for(int j:P){
            if(vis[j] == timer || (int)g[j].size() <= k) continue;
            dfs(j);
            ss += dp[j][0];
        }
        res.push_back(ss);
    }
    return res;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 7
• Subtask 3: 14 / 14
• Subtask 4: 10 / 10
• Subtask 5: 0 / 17
• Subtask 6: 0 / 25
• Subtask 7: 0 / 22