Submission #555956

#	Time	Username	Problem	Language	Result	Execution time	Memory
555956		aryan12	Road Closures (APIO21_roads)	C++17	24 / 100	2093 ms	21768 KiB

roads

#include "roads.h"
#include <bits/stdc++.h>
using namespace std;

const long long MAXN = 1e5 + 5;
vector<array<long long, 2> > g[MAXN];
long long n, k;
vector<array<long long, 2> > dp(MAXN);
// dp[node][0] -- parent weight not selected
// dp[node][1] -- parent weight selected

void dfs(long long node, long long par, long long par_wt)
{
    // if(k == 1) cout << "node = " << node << ", par = " << par << ", par_wt = " << par_wt << "\n";
    if(g[node].size() == 1 && par != -1) // base case
    {
        dp[node][0] = 0;
        dp[node][1] = par_wt;
        return;
    }
    long long sum = 0;
    vector<long long> diff;
    for(auto [to, wt]: g[node])
    {
        if(to != par)
        {
            dfs(to, node, wt);
            sum += dp[to][0];
            diff.push_back(dp[to][1] - dp[to][0]);
        }
    }
    sort(diff.begin(), diff.end());
    reverse(diff.begin(), diff.end());
    long long gg = diff.size();
    for(long long i = diff.size() - 1; i >= 0; i--)
    {
        if(diff[i] < 0)
        {
            gg = i;
        }
    }
    // if(k == 1) cout << "node = " << node << ", diff.size() = " << diff.size() << "\n";
    long long children_siz = g[node].size() - 1;
    // no. of children + parent <= k
    if(children_siz + 1 <= k)
    {
        for(long long i = diff.size() - 1; i >= gg; i--)
        {
            sum += diff[i];
        }
        dp[node][0] = sum;
        dp[node][1] = sum + par_wt;
        return;
    }
    // if(k == 1) cout << "node has reached here\n";
    // keeping edges between k - 1 children and parent
    long long buffer_value = 0;
    for(long long i = diff.size() - 1; i >= min(gg, k - 1); i--)
    {
        buffer_value += diff[i];
    }
    dp[node][0] = sum + buffer_value;
    // keeping edges between k children only
    buffer_value = par_wt;
    for(long long i = diff.size() - 1; i >= min(k, gg); i--)
    {
        buffer_value += diff[i];
    }
    dp[node][1] = sum + buffer_value;
}

long long calculatedp()
{
    for(long long i = 0; i <= n; i++)
    {
        dp[i][0] = 0;
        dp[i][1] = 0;
    }
    dfs(0, -1, 0);
    if(k == 1)
    {
        // cout << "dp values\n";
        // for(int i = 0; i < n; i++)
        // {
        //     cout << dp[i][0] << " " << dp[i][1] << "\n";
        // }
    }
    return min(dp[0][0], dp[0][1]);
}

vector<long long> minimum_closure_costs(int N, vector<int> U, vector<int> V, vector<int> W) 
{
    n = N;
    long long sum = 0;
    for(long long i = 0; i < U.size(); i++)
    {
        sum += W[i];
        // cout << "U[i] = " << U[i] << ", V[i] = " << V[i] << ", W[i] = " << W[i] << "\n";
        g[U[i]].push_back({V[i], W[i]});
        g[V[i]].push_back({U[i], W[i]});
    }
    vector<long long> ans;
    ans.push_back(sum);
    for(long long i = 1; i < N; i++)
    {
        k = i;
        ans.push_back(calculatedp());
    }
    return ans;
}

Compilation message (stderr)

roads.cpp: In function 'std::vector<long long int> minimum_closure_costs(int, std::vector<int>, std::vector<int>, std::vector<int>)':
roads.cpp:95:28: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   95 |     for(long long i = 0; i < U.size(); i++)
      |                          ~~^~~~~~~~~~

• 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