Submission #306587

#	Time	Username	Problem	Language	Result	Execution time	Memory
306587		Marlov	Ball Machine (BOI13_ballmachine)	C++14	47.88 / 100	1087 ms	21496 KiB

ballmachine

/*
Code by @marlov       
*/
#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <iomanip>
#include <utility>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <stack>
#include <queue>
#include <iterator>
using namespace std;
typedef long long ll;
typedef pair<int,int> pi;

#define maxN 100005

int N,Q;
int bl[maxN][16];
bool hasB[maxN];

//tree setup
vector<int> adj[maxN];
int stmin[maxN];
int ordering[maxN];

bool cmp(int a,int b){
	return stmin[a]<stmin[b];
}

void dfs1(int n,int p){
	if(adj[n].size()==0){
		stmin[n]=n;
		return;
	}
	for(int a:adj[n]) if(a!=p){
		dfs1(a,n);
	}
	sort(adj[n].begin(),adj[n].end(),cmp);
	stmin[n]=stmin[adj[n].front()];
}
int cno=0;
void dfs2(int n,int p){
	for(int a:adj[n]) if(n!=p){
		dfs2(a,n);
	}
	ordering[cno]=n;
	cno++;
}

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);
	cin>>N>>Q;
	N++;
	bl[0][0]=0;
	int cnp;
	for(int i=1;i<N;i++){
		cin>>cnp;
		bl[i][0]=cnp;
		adj[cnp].push_back(i);
		//adj[i].push_back(cnp);
	}
	
	for(int j=1;j<16;j++){
		for(int i=0;i<N;i++){
			bl[i][j]=bl[bl[i][j-1]][j-1];
		}
	}
	//order-processing
	dfs1(0,-1);
	dfs2(0,-1);
	int t,v;
	for(int i=0;i<Q;i++){
		cin>>t>>v;
		if(t==1){
			for(int i=0;i<N;i++){
				if(hasB[ordering[i]]==false){
					hasB[ordering[i]]=true;
					v--;
				}
				if(v==0||i==N-1){
					cout<<ordering[i]<<'\n';
					break;
				}
			}
		}else if(t==2){
			int cn=v;
			int tl=0;
			for(int j=15;j>=0;j--){
				while(cn!=0&&hasB[bl[cn][j]]==true){
					cn=bl[cn][j];
					tl+=(1<<j);
				}
			}
				cout<<tl<<'\n';
				hasB[cn]=false; 
		}
	}
    return 0;
}

/* stuff you should look for
	* int overflow, array bounds
	* special cases (n=1,n=0?)
	* do smth instead of nothing and stay organized
*/

• Subtask 1: 1.9230769230769231 / 25
• Subtask 2: 12.857142857142858 / 30
• Subtask 3: 31.428571428571427 / 40
• Subtask 4: 1.6666666666666667 / 5