Submission #1073347

#	Time	Username	Problem	Language	Result	Execution time	Memory
1073347		Unforgettablepl	Closing Time (IOI23_closing)	C++17	75 / 100	1010 ms	2097152 KiB

closing

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

const long long INF = 1e18+1;

int max_score(int N,int X,int Y,long long K,
              vector<int> U,vector<int> V,vector<int> W){
    vector<vector<pair<int,long long>>> adj(N);
    for(int i=0;i<N-1;i++) {
        adj[U[i]].emplace_back(V[i],W[i]);
        adj[V[i]].emplace_back(U[i],W[i]);
    }
    vector<long long> distX(N);
    vector<long long> distY(N);
    auto dijkastra = [&](int x) {
        priority_queue<pair<long long,int>> pq;
        pq.emplace(0,x);
        vector<bool> visited(N);
        while(!pq.empty()) {
            auto [dist,idx] = pq.top();pq.pop();dist=-dist;
            if(visited[idx])continue;
            visited[idx]=true;
            distX[idx]=dist;
            for(auto[v,c]:adj[idx])if(!visited[v])pq.emplace(-dist-c,v);
        }
    };
    dijkastra(Y);
    swap(distX,distY);
    dijkastra(X);
    vector cost1(N+1,0ll);
    vector cost2(N+1,0ll);
    for(int i=0;i<N;i++) {
        long long mini = min(distX[i],distY[i]);
        long long maxi = max(distX[i],distY[i]);
        cost1[i+1] = mini;
        cost2[i+1] = maxi;
    }
    int simple_ans = 0;
    {
        auto c = cost1;
        sort(c.begin(), c.end());
        long long sum = 0;
        for(int i=1;i<=N;i++) {
            sum+=c[i];
            if(sum<=K)simple_ans=i;
        }
    }
    vector onPath(N,false);
    {
        function<bool(int,int)> dfs = [&](int x,int p) {
            if(x==Y) {
                onPath[x]=true;
                return true;
            }
            for(auto[v,c]:adj[x])if(v!=p) {
                if(dfs(v,x)) {
                    onPath[x]=true;
                    return true;
                }
            }
            return false;
        };
        assert(dfs(X,-1));
    }
    vector DP(N+1,vector(2*N+1,INF));
    DP[0][0]=0;
    for(int i=1;i<=N;i++) {
        for(int j=0;j<=2*N;j++) {
            if(!onPath[i-1])DP[i][j]=min(DP[i][j],DP[i-1][j]);
            if(j>0)DP[i][j]=min(DP[i][j],DP[i-1][j-1]+cost1[i]);
            if(j>1)DP[i][j]=min(DP[i][j],DP[i-1][j-2]+cost2[i]);
        }
    }
    for(int j=2*N;j;j--)if(DP[N][j]<=K)return max(j,simple_ans);
    return simple_ans;
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 8
• Subtask 2: 9 / 9
• Subtask 3: 12 / 12
• Subtask 4: 14 / 14
• Subtask 5: 9 / 9
• Subtask 6: 11 / 11
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 0 / 17