Submission #1066948

#	Time	Username	Problem	Language	Result	Execution time	Memory
1066948		pcc	Beech Tree (IOI23_beechtree)	C++17	5 / 100	190 ms	72364 KiB

beechtree

#include "beechtree.h"
#include <bits/stdc++.h>
using namespace std;

#define pii pair<int,int>
#define fs first
#define sc second

const int mxn = 2e5+10;

vector<pii> tree[mxn];
pii par[mxn];
int dep[mxn];
vector<int> lvl[3];
set<int> st[mxn];
vector<int> ans;
vector<int> col[mxn];
bitset<mxn> active;
pii eul[mxn];
int ptr = 0;

void dfs(int now){
	eul[now].fs = ++ptr;
	for(auto [nxt,w]:tree[now]){
		dfs(nxt);
		if(!ans[nxt])ans[now] = 0;
		if(st[now].size()<st[nxt].size())st[now].swap(st[nxt]);
		for(auto &i:st[nxt])st[now].insert(i);
		st[now].insert(w);
	}
	eul[now].sc = ptr;
	if(st[now].size() != tree[now].size())ans[now] = 0;
	int tar = -1;
	for(auto [nxt,w]:tree[now]){
		if(col[w].size()<2)continue;
		int now = (col[w][0] == now?col[w][1]:col[w][0]);
		if(tar == -1)tar = now;
		else if(now != tar)ans[now] = 0;
	}
	return;
}

std::vector<int> beechtree(int N, int M, std::vector<int> P, std::vector<int> C){
	ans = vector<int>(N,1);
	for(int i = 1;i<N;i++){
		int p = P[i];
		tree[p].push_back(pii(i,C[i]));
		par[i] = pii(p,C[i]);
		col[C[i]].push_back(p);
	}
	dfs(0);
	return ans;
}

Compilation message (stderr)

beechtree.cpp: In function 'void dfs(int)':
beechtree.cpp:36:30: warning: 'now' may be used uninitialized in this function [-Wmaybe-uninitialized]
   36 |   int now = (col[w][0] == now?col[w][1]:col[w][0]);
      |             ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 0 / 9
• Subtask 2: 5 / 5
• Subtask 3: 0 / 9
• Subtask 4: 0 / 8
• Subtask 5: 0 / 14
• Subtask 6: 0 / 14
• Subtask 7: 0 / 12
• Subtask 8: 0 / 17
• Subtask 9: 0 / 12