Submission #736614

#	Time	Username	Problem	Language	Result	Execution time	Memory
736614		josanneo22	Cat in a tree (BOI17_catinatree)	C++17	100 / 100	13 ms	6300 KiB

catinatree

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

#define pb push_back
#define pii pair<int,int>
const int inf=1000000010;
const int MAXN=200010, LOG=20;
char buf[1<<23],*p1=buf,*p2=buf;
#define getchar() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
inline int rd()
{
	int s=0;
	char ch=getchar(),last;
	while(ch<'0'||ch>'9') last=ch,ch=getchar();
	while(ch>='0'&&ch<='9') s=(s<<1)+(s<<3)+(ch^48),ch=getchar();
	return last=='-'?-s:s;
}
int num[100];
inline void rt(int x)
{
	if(x<0) putchar('-'),x=-x;;
	int len=0;
	do num[len++]=x%10;while(x/=10);
	while(len--) putchar(num[len]+'0');
}

int n, D;
int par[MAXN];
pii dp[MAXN][2], dpt[2];
 
inline void Add(int v, int u){
	for (int i:{0, 1}) dpt[i]=dp[v][i];
	for (int i:{0, 1}) for (int j:{0, 1}) if (dpt[i].second+dp[u][j].second>=D){
		pii p={dpt[i].first+dp[u][j].first, min(dpt[i].second, dp[u][j].second)};
		if (p>dp[v][0]) swap(dp[v][0], p);
		if (p.first!=dp[v][0].first && p>dp[v][1]) swap(dp[v][1], p);
	}
}

void solve(){
	n=rd(),D=rd();
	for (int i=1; i<n; i++)par[i]=rd();
	for (int i=0; i<n; i++) dp[i][0]={1, 0}, dp[i][1]={0, inf};
	for (int i=n-1; i; i--){
		dp[i][0].second++;
		dp[i][1].second++;
		Add(par[i], i);
	}
	rt(dp[0][0].first);
}
int main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	solve();
}

Compilation message (stderr)

catinatree.cpp: In function 'int rd()':
catinatree.cpp:16:18: warning: 'last' may be used uninitialized in this function [-Wmaybe-uninitialized]
   16 |  return last=='-'?-s:s;
      |         ~~~~~~~~~^~~~~

• Subtask 1: 11 / 11
• Subtask 2: 40 / 40
• Subtask 3: 49 / 49