Submission #305039

#	Time	Username	Problem	Language	Result	Execution time	Memory
305039		vipghn2003	Race (IOI11_race)	C++14	100 / 100	567 ms	83192 KiB

race

#include<bits/stdc++.h>
#define fi first
#define se second
#define pii pair<int,int>
using namespace std;

const int N=2e5+5;
int res,k;
map<int,int>mp[N];
vector<pii>adj[N];

void dfs(int u,int p=-1,int h=0,int w=0)
{
    mp[u][w]=h;
    int tmp=u;
    for(auto&to:adj[u])
    {
        int v=to.fi;
        if(v==p) continue;
        dfs(v,tmp,h+1,w+to.se);
        if(mp[u].size()<mp[v].size()) swap(mp[u],mp[v]);
        for(auto&x:mp[v])
        {
            if(mp[u].count(k+2*w-x.fi))
            {
                res=min(res,x.se+mp[u][k+2*w-x.fi]-2*h);
            }
        }
        for(auto&x:mp[v])
        {
            if(!mp[u].count(x.fi)||mp[u][x.fi]>x.se) mp[u][x.fi]=x.se;
        }
    }
}


int best_path(int n,int nk,int h[][2],int l[])
{
    k=nk;
    for(int i=0;i<n-1;i++)
    {
        adj[h[i][0]].push_back(make_pair(h[i][1],l[i]));
        adj[h[i][1]].push_back(make_pair(h[i][0],l[i]));
    }
    res=1e9;
    dfs(0);
    if(res==1e9) res=-1;
    return res;
}
/*
int main()
{
    int n,k;
    cin>>n>>k;
    int h[n][2],l[n];
    for(int i=0;i<n-1;i++) cin>>h[i][0]>>h[i][1];
    for(int i=0;i<n-1;i++) cin>>l[i];
    cout<<best_path(n,k,h,l);
}

4 3
0 1
1 2
1 3
1 2 4
*/

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