Submission #725701

#	Time	Username	Problem	Language	Result	Execution time	Memory
725701		sofija6	Race (IOI11_race)	C++14	21 / 100	3072 ms	10332 KiB

race

#include <bits/stdc++.h>
#include "race.h"
#define MAXN 200010
#define MAXK 1000010
using namespace std;
vector<pair<int,int> > G[MAXN];
bool check[MAXN];
int subtree[MAXN],k,res=INT_MAX,ans[MAXK];
void DFS_Subtree(int i,int p)
{
    subtree[i]=1;
    for (auto next : G[i])
    {
        if (next.first!=p && !check[next.first])
        {
            DFS_Subtree(next.first,i);
            subtree[i]+=subtree[next.first];
        }
    }
}
int DFS_Centroid(int i,int p,int root)
{
    for (auto next : G[i])
    {
        if (next.first!=p && !check[next.first] && subtree[next.first]>subtree[root]/2)
            return DFS_Centroid(next.first,i,root);
    }
    return i;
}
void DFS_Paths(int i,int p,int d,int cnt)
{
    if (d>k)
        return;
    if (ans[k-d])
        res=min(res,ans[k-d]+cnt);
    for (auto next : G[i])
    {
        if (next.first!=p)
            DFS_Paths(next.first,i,d+next.second,cnt+1);
    }
}
void DFS_Fill(int i,int p,int d,int cnt)
{
    if (d>k)
        return;
    ans[d]=(!ans[d])?cnt : min(ans[d],cnt);
    for (auto next : G[i])
    {
        if (next.first!=p)
            DFS_Fill(next.first,i,d+next.second,cnt+1);
    }
}
void Solve(int i)
{
    DFS_Subtree(i,i);
    int c=DFS_Centroid(i,i,i);
    check[c]=true;
    for (int i=0;i<=k;i++)
        ans[i]=0;
    for (auto next : G[c])
    {
        DFS_Paths(next.first,c,next.second,1);
        DFS_Fill(next.first,c,next.second,1);
    }
    for (auto next : G[c])
    {
        if (!check[next.first])
            Solve(next.first);
    }
}
int best_path(int N, int K, int H[][2], int L[])
{
    k=K;
    for (int i=0;i<N-1;i++)
    {
        G[H[i][0]].push_back({H[i][1],L[i]});
        G[H[i][1]].push_back({H[i][0],L[i]});
    }
    Solve(0);
    return (res==INT_MAX?-1 : res);
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57