Submission #677847

#	Time	Username	Problem	Language	Result	Execution time	Memory
677847		Baytoro	Regions (IOI09_regions)	C++17	100 / 100	3995 ms	118492 KiB

regions

#include <bits/stdc++.h>
using namespace std;
#define ios ios::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL);
#define pb push_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define fr first
#define sc second
#define endl '\n'
void fopn(string name){
	freopen((name+".in").c_str(),"r",stdin);
	freopen((name+".out").c_str(),"w",stdout);
}
//const long long INF=1e18,mod=998244353;

const int N=2e5+5,block=25005;
int a[N],st[N],ed[N],B[N],used[N];
vector<int> g[N],v[block];
int cnt=1;
unordered_map<int,int> clc[block];
void dfs(int x, int p=-1){
	st[x]=cnt++;
	for(auto it: g[x]){
		if(it==p) continue;
		dfs(it,x);
	}
	ed[x]=cnt-1;
}
int n,r,q;
void solve(){
	cin>>n>>r>>q>>a[1];
	for(int i=2;i<=n;i++){
		int x;cin>>x>>a[i];
		g[x].pb(i);
	}
	int K=sqrt(n);
	dfs(1);
	for(int i=1;i<=n;i++) B[st[i]]=i;
	for(int i=1;i<=n;i++) v[a[B[i]]].pb(st[B[i]]);
	//--------------------------------------------
	for(int i=1;i<=n;i++){
		if(used[a[B[i]]]) continue;
		if((int)v[a[B[i]]].size()<=K) continue;
		used[a[B[i]]]=1;
		int pref[n+2]{0};
		for(auto it: v[a[B[i]]]){
			int l=st[B[it]],r=ed[B[it]];
			pref[l]++;
			pref[r+1]--;
		}
		for(int j=1;j<=n;j++)
			pref[j]+=pref[j-1],clc[a[B[j]]][a[B[i]]]+=pref[j];
	}
	//---------------------------------------------
	while(q--){
		int a,b;cin>>a>>b;
		int ans=0;
		if((int)v[a].size()<=K){
			for(auto it: v[a]){
				int l=st[B[it]],r=ed[B[it]];
				auto i1=upper_bound(all(v[b]),r)-v[b].begin();
				auto i2=upper_bound(all(v[b]),l)-v[b].begin();
				if(i1)
					ans+=max((int)(i1-i2),0);
			}
		}
		else
			ans=clc[b][a];
		cout<<ans<<endl;
	}
}
main(){
	//fopn("newbarn");
	//ios;
	int T=1;
	//cin>>T;
	while(T--){
		solve();
	}
}

Compilation message (stderr)

regions.cpp:72:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   72 | main(){
      | ^~~~
regions.cpp: In function 'void fopn(std::string)':
regions.cpp:11:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |  freopen((name+".in").c_str(),"r",stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
regions.cpp:12:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |  freopen((name+".out").c_str(),"w",stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 85 / 85