Submission #557569

#	Time	Username	Problem	Language	Result	Execution time	Memory
557569		krit3379	Railway (BOI17_railway)	C++17	100 / 100	196 ms	41380 KiB

railway

#include<bits/stdc++.h>
using namespace std;
#define N 100005
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

int t[4*N],cnt[N],dep[N],head[N],heavy[N],p[N],id[N],out[N],last[N],sz;
vector<int> v,temp,ans;
bitset<N> vis;
vector<pair<int,int>> g[N];

void dfs(int s,int f){
    int ma=0;
    cnt[s]=1;
    dep[s]=dep[f]+1;
    heavy[s]=-1;
    p[s]=f;
    for(auto [x,i]:g[s]){
        if(x==f)continue;
        out[x]=i;
        dfs(x,s);
        cnt[s]+=cnt[x];
        if(cnt[x]>ma)ma=cnt[x],heavy[s]=x;
    }
}

void hld(int s,int f,int h){
    head[s]=h;
    id[s]=++sz;
    if(heavy[s]!=-1)hld(heavy[s],s,h);
    for(auto [x,i]:g[s]){
        if(x==f||x==heavy[s])continue;
        hld(x,s,x);
    }
    return ;
}

int lca(int a,int b){
    while(head[a]!=head[b]){
        if(dep[head[a]]>dep[head[b]])a=p[head[a]];
        else b=p[head[b]];
    }
    if(dep[a]<dep[b])return a;
    else return b;
}

void push(int x,int l,int r){
    if(t[x]&&l!=r){
        t[x*2]+=t[x];
        t[x*2+1]+=t[x];
        t[x]=0;
    }
}

void upd(int x,int l,int r,int ll,int rr){
    push(x,l,r);
    if(l>rr||ll>r||ll>rr)return ;
    if(ll<=l&&r<=rr){
        t[x]++;
        push(x,l,r);
        return ;
    }
    int mid=(l+r)/2;
    upd(x*2,l,mid,ll,rr);
    upd(x*2+1,mid+1,r,ll,rr);
}

void update(int a,int l){
    while(head[a]!=head[l]){
        upd(1,1,sz,max(id[head[a]],last[head[a]]+1),id[a]);
        last[head[a]]=max(last[head[a]],id[a]);
        if(!vis[head[a]])vis[head[a]]=true,temp.push_back(head[a]);
        a=p[head[a]];
    }
    if(a!=l){
        upd(1,1,sz,max(id[l]+1,last[head[a]]+1),id[a]);
        last[head[a]]=max(last[head[a]],id[a]);
        if(!vis[head[a]])vis[head[a]]=true,temp.push_back(head[a]);
    }
}

int sol(int x,int l,int r,int p){
    push(x,l,r);
    if(l>p||p>r)return 0;
    if(l==r)return t[x];
    int mid=(l+r)/2;
    return sol(x*2,l,mid,p)+sol(x*2+1,mid+1,r,p);
}

int main(){
    int n,m,k,i,a,b,t,x,l;
    scanf("%d %d %d",&n,&m,&k);
    for(i=1;i<n;i++){
        scanf("%d %d",&a,&b);
        g[a].push_back({b,i});
        g[b].push_back({a,i});
    }
    dfs(1,0);
    hld(1,0,1);
    while(m--){
        scanf("%d",&t);
        for(i=1;i<=t;i++)scanf("%d",&x),v.push_back(x);
        l=v[0];
        for(i=1;i<v.size();i++)l=lca(l,v[i]);
        for(auto x:v)update(x,l);
        for(auto x:temp)last[x]=0,vis[x]=false;
        v.clear();
        temp.clear();
    }
    for(i=1;i<=n;i++)if(sol(1,1,n,id[i])>=k)ans.push_back(out[i]);
    sort(ans.begin(),ans.end());
    printf("%d\n",ans.size());
    for(auto x:ans)printf("%d ",x);
    return 0;
}

Compilation message (stderr)

railway.cpp: In function 'int main()':
railway.cpp:104:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  104 |         for(i=1;i<v.size();i++)l=lca(l,v[i]);
      |                 ~^~~~~~~~~
railway.cpp:112:14: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wformat=]
  112 |     printf("%d\n",ans.size());
      |             ~^    ~~~~~~~~~~
      |              |            |
      |              int          std::vector<int>::size_type {aka long unsigned int}
      |             %ld
railway.cpp:92:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |     scanf("%d %d %d",&n,&m,&k);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~
railway.cpp:94:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   94 |         scanf("%d %d",&a,&b);
      |         ~~~~~^~~~~~~~~~~~~~~
railway.cpp:101:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |         scanf("%d",&t);
      |         ~~~~~^~~~~~~~~
railway.cpp:102:31: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |         for(i=1;i<=t;i++)scanf("%d",&x),v.push_back(x);
      |                          ~~~~~^~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 7 / 7
• Subtask 4: 29 / 29
• Subtask 5: 16 / 16
• Subtask 6: 25 / 25