Submission #504022

#	Time	Username	Problem	Language	Result	Execution time	Memory
504022		tgbegimx	Untitled (POI11_dyn)	C++17	70 / 100	578 ms	41148 KiB

Main

#include <bits/stdc++.h>
#define fast ios_base::sync_with_stdio(0) ; cin.tie(0);cout.tie(0)
#define ll long long
#define foru(i,l,r) for(int i=l;i<=r;i++)
#define ford(i,l,r) for(int i=l;i>=r;i--)
#define pb push_back
using namespace std;
const int N=2e5+10;
vector<int> d;
vector<vector<int>> ke;
int f[N],num,kt[N];
int n,m;
void dfs(int k,int u,int fa)
{
    int mx1=-1e9,mx2=-1e9;
    if(d[u]) mx1=0;
    for(auto v:ke[u])
    if(v!=fa)
    {
        //cout<<v<<' ';
        dfs(k,v,u);
        if(kt[v]==1) mx1=max(mx1,f[v]+1);
        if(kt[v]==2) mx2=max(mx2,f[v]-1);
    }
    if(mx1>mx2)
    {
        if(mx1>=k)
        {
          ++num,kt[u]=2,f[u]=k;
          if(num>m) kt[u]=-1;
        }
        else kt[u]=1,f[u]=mx1;
    }
    else kt[u]=2,f[u]=mx2;

}
bool check(int k)
{
    num=0;
    dfs(k,1,-1);
    //cout<<'\n';
    if(kt[1]==-1) return 0;
    if(kt[1]==1&&f[1]>=0) ++num;
    return num<=m;
}
void solve()
{
    cin>>n>>m;
    d.resize(n+1);
    ke.resize(n+5);
    foru(i,1,n) cin>>d[i];
    foru(i,1,n-1)
    {
        int u,v;
        cin>>u>>v;
        ke[u].pb(v);
        ke[v].pb(u);
    }
    //for(auto v:ke[5]) cout<<v<<' ';
    int l=0,r=n;
    int ans=0;
    while(l<=r)
    {
        int mid=(l+r)>>1;
        //cout<<check(mid)<<' ';
        if(check(mid)) ans=mid,r=mid-1;
        else l=mid+1;
    }
    cout<<ans;
}
int main()
{
    //freopen("main.inp","r",stdin);
    //freopen("main.out","w",stdout);
    fast;
    int t=1;
    //cin>>t;
    while(t--)
       solve();

}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10