Submission #947687

#	Time	Username	Problem	Language	Result	Execution time	Memory
947687		PM1	Sumtree (INOI20_sumtree)	C++17	10 / 100	303 ms	278152 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fr first
#define sc second
const int mxn=5e5+5,M=1e9+7,kkk=(1<<21);
int n,q,r,st[mxn],fn[mxn],cnt=0,sz[mxn],g[mxn],bbb;
ll ans,fuck[mxn],rfuck[mxn];
vector<int>v[mxn];
ll ferma(ll x){
	ll num=M-2,res=1;
	while(num){
		if(num&1)res=(res*x)%M;
		x=(x*x)%M;
		num/=2;
	}
	return res;
}
void dfs(int z){
	sz[z]=1;
	st[z]=++cnt;
	for(auto i:v[z]){
		if(!st[i]){
			dfs(i);
			sz[z]+=sz[i];
		}
	}
	fn[z]=cnt;
}
void make(){
	fuck[0]=rfuck[0]=1;
	for(int i=1;i<=n+r;i++){
		fuck[i]=(fuck[i-1]*i)%M;
		rfuck[i]=ferma(fuck[i]);
	}
}
ll comb(int x,int y,bool w){
	if(x>y){
		bbb+=(w)?-1:1;
		return 1;
	}
	ll res=fuck[y]*rfuck[x];
	res%=M;
	res*=rfuck[y-x];
	return res%M;
}
struct segment{
	ll val[kkk];
	void up(int id,int L,int R,int l,int x){
		if(L+1==R){
			val[id]=x;
			return;
		}
		int mid=(L+R)/2;
		if(l<mid)
			up(id*2,L,mid,l,x);
		else
			up(id*2+1,mid,R,l,x);
		val[id]=val[id*2]+val[id*2+1];
	}
	ll get(int id ,int L,int R,int l,int r){
		if(L==l && R==r)
			return val[id];
		int mid=(L+R)/2;
		ll res=0;
		if(l<mid)
			res+=get(id*2,L,mid,l,min(r,mid));
		if(r>mid)
			res+=get(id*2+1,mid,R,max(l,mid),r);
		return res;
	}
}seg[2];
struct fnd{
	set<int>s[kkk];
	int get(int id,int L,int R,int l,int r){
		if(L==l && R==r)
			return ((s[id].size())?*s[id].rbegin():0);
		int mid=(L+R)/2,res=((s[id].size())?*s[id].rbegin():0),x=0;
		if(l<mid){
			x=get(id*2,L,mid,l,min(r,mid));
		}
		return (x)?x:res;
	}
	void add(int id ,int L,int R,int l,int r,int x,bool y){
		if(L==l && R==r){
			if(y)
				s[id].insert(x);
			else
				s[id].erase(x);
			return;
		}
		int mid=(L+R)/2;
		if(l<mid)
			add(id*2,L,mid,l,min(r,mid),x,y);
		if(r>mid)
			add(id*2+1,mid,R,max(l,mid),r,x,y);
	}
}fnd;
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>r;
	for(int i=1;i<n;i++){
		int x,y;
		cin>>x>>y;
		v[x].push_back(y);
		v[y].push_back(x);
	}
	dfs(1);
	make();
	ans=comb(n-1,n+r-1,0);
	seg[0].up(1,1,n+1,1,n);
	seg[1].up(1,1,n+1,1,r);
	fnd.add(1,1,n+1,1,n+1,1,1);
	g[1]=r;
	cout<<ans<<'\n';
	cin>>q;
	while(q--){
		int ty,x,y,z;
		cin>>ty;
		if(ty==1){
			cin>>x>>g[x];
			z=fnd.get(1,1,n+1,st[x],fn[x]+1);
			fnd.add(1,1,n+1,st[x],fn[x]+1,st[x],1);
		}
		
		
		int t1=seg[0].get(1,1,n+1,st[x],fn[x]+1)-seg[0].get(1,1,n+1,st[x],st[x]+1);
		int t2=seg[0].get(1,1,n+1,st[z],fn[z]+1)-seg[0].get(1,1,n+1,st[z],st[z]+1);
		ll v1=0;
		ll v2=0;
		if(ty==1){
			int sz1=sz[x]-t1;
			int sz2=sz[z]-t2-sz1;
			seg[0].up(1,1,n+1,st[x],sz1);
			seg[0].up(1,1,n+1,st[z],sz2);

			ans*=ferma(comb(sz[z]-t2-1,sz[z]-t2+v2-1,1));
			ans%=M;
			//cout<<comb(sz[z]-t2-1,sz[z]-t2+v2-1,1)<<" ";
			int val1=comb(sz1-1,sz1-1+g[x]-v1,0);
			int val2=comb(sz2-1,sz2-1+v2-g[x]+v1,0);
			ans*=val1;
			ans%=M;
			ans*=val2;
			ans%=M;
			
		}
		
		if(bbb){
			cout<<0<<'\n';
		}
		else
			cout<<ans<<'\n';
	}
	return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:120:12: warning: unused variable 'y' [-Wunused-variable]
  120 |   int ty,x,y,z;
      |            ^
Main.cpp:139:35: warning: 'z' may be used uninitialized in this function [-Wmaybe-uninitialized]
  139 |    ans*=ferma(comb(sz[z]-t2-1,sz[z]-t2+v2-1,1));
      |                               ~~~~^

• Subtask 1: 10 / 10
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30