Submission #697610

#	Time	Username	Problem	Language	Result	Execution time	Memory
697610		Dan4Life	Road Closures (APIO21_roads)	C++17	36 / 100	247 ms	6624 KiB

roads

#include "roads.h"
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(),a.end()
using ll = long long;
const int mxN = (int)2e3+10;
const ll LINF = (ll)1e18;

int n, k;
ll dp[mxN][2];
vector<pair<int,ll>> adj[mxN];

void dfs(int s, int p){
    vector<int> v; v.clear();
    for(auto x : adj[s]){
        int u = x.fi; ll w = x.se;
        if(u!=p) dfs(u,s), dp[u][0]+=w, v.pb(u);
    }
    sort(all(v), [&](int a, int b){
        return dp[a][1]-dp[a][0]<dp[b][1]-dp[b][0];
    });
    for(int x = 0; auto u : v){
        if(x<k) dp[s][0]+=min(dp[u][0],dp[u][1]);
        else dp[s][0]+=dp[u][0];
        if(x<k-1) dp[s][1]+=min(dp[u][0],dp[u][1]);
        else dp[s][1]+=dp[u][0];
        x++;
    }
}

vector<ll> minimum_closure_costs(int N, vector<int> U, vector<int> V, vector<int> W) {
    n = N;
    vector<ll> ans(N,0ll);
    ans[0] = accumulate(all(W),0ll);
    if(accumulate(all(U),0ll)==0ll){
        sort(all(W)); reverse(all(W)); int i = 0;
        ll tot = accumulate(all(W),0ll);
        for(auto &u : ans) u=tot,tot-=W[i++];
        return ans;
    }
    bool isLine = 1;
    for(int i = 0; i < N-1; i++)
        isLine &= (U[i]==i and V[i]==i+1);
    if(isLine){
        ll dp[N-1][2];
        dp[0][0] = dp[0][1] = 0;
        for(int i = 1; i < N; i++){
            dp[i][0] = min(dp[i-1][1],dp[i-1][0])+W[i-1];
            dp[i][1] = dp[i-1][0];
        }
        ans[1] = min(dp[N-1][0],dp[N-1][1]);
        return ans;
    }
    for(int i = 0; i < N-1; i++){
        adj[U[i]].pb({V[i],W[i]});
        adj[V[i]].pb({U[i],W[i]});
    }
    for(k = 1; k < n; k++)
        memset(dp,0,sizeof(dp)), dfs(0,-1), ans[k]=dp[0][0];
    return ans;
}

Compilation message (stderr)

roads.cpp: In function 'void dfs(int, int)':
roads.cpp:27:20: warning: range-based 'for' loops with initializer only available with '-std=c++2a' or '-std=gnu++2a'
   27 |     for(int x = 0; auto u : v){
      |                    ^~~~

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