Submission #469081

#	Time	Username	Problem	Language	Result	Execution time	Memory
469081		Josia	Chase (CEOI17_chase)	C++14	70 / 100	1098 ms	17820 KiB

chase

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx2")


#include <bits/stdc++.h>

#define int int64_t

using namespace std;


vector<int> nearbyPigeons;
vector<int> pigeons;
vector<vector<int>> graph;
int crumbs;


void findNearPigeons(int v, int p) {
    if (p!=-1) nearbyPigeons[v] += pigeons[p];

    for (int i: graph[v]) {
        if (i==p) continue;
        nearbyPigeons[v] += pigeons[i];
        findNearPigeons(i, v);
    }
}




vector<int> options;        // all paths


map<int, int> localOptions; // one path for selecting crumbs


void findBestOptions(int v, int p) {
    int addToLocalOptions;
    if (p==-1) addToLocalOptions = nearbyPigeons[v];
    else addToLocalOptions = nearbyPigeons[v]-pigeons[p];

    for (int i: graph[v]) {
        if (i==p) continue;

        localOptions[addToLocalOptions]++;

        findBestOptions(i, v);

        localOptions[addToLocalOptions]--;
        if (localOptions[addToLocalOptions] == 0) localOptions.erase(addToLocalOptions);
    }


    localOptions[addToLocalOptions]++;

    int addToOptions = 0;

    auto pos = localOptions.end();
    auto limit = localOptions.begin();
    pos--;
    int used = crumbs;
    while (used>0 && pos!=limit) {
        addToOptions+=(*pos).first*min((*pos).second, used);
        used -= min((*pos).second, used);
        pos--;
    }

    if (used) {
        addToOptions+=(*pos).first*min((*pos).second, used);
        used -= min((*pos).second, used);
    }

    assert(used >= 0);

    options.push_back(addToOptions);


    localOptions[addToLocalOptions]--;
    if (localOptions[addToLocalOptions] == 0) localOptions.erase(addToLocalOptions);
}




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

    int n; cin >> n >> crumbs;

    pigeons.assign(n, 0);
    nearbyPigeons.assign(n, 0);

    for (int i = 0; i<n; i++) cin >> pigeons[i];


    graph.assign(n, vector<int>(0));

    for (int i = 1; i<n; i++) {
        int a, b; cin >> a >> b;
        a--; b--;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }

    findNearPigeons(0, -1);

    // for (int i: nearbyPigeons) {
    //     cout << i << " ";
    // }
    // cout << "\n";



    int best = 0;
    if (n>1000) {
    for (int i = 0; i<1; i++) {
        options.clear();
        findBestOptions(i, -1);

        // for (int i: options) {
        //     cout << i << " ";
        // }
        // cout << "\n";


        best = max(best, *max_element(options.begin(), options.end()));
        
    }}
    else {
        for (int i = 0; i<n; i++) {
        options.clear();
        findBestOptions(i, -1);

        // for (int i: options) {
        //     cout << i << " ";
        // }
        // cout << "\n";


        best = max(best, *max_element(options.begin(), options.end()));
        
    }
    }

    cout << best << "\n";




    return 0;
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 0 / 30