Submission #726603

#	Time	Username	Problem	Language	Result	Execution time	Memory
726603		Mauve	Race (IOI11_race)	C++14	0 / 100	2 ms	4948 KiB

race

#include "race.h"
#include<bits/stdc++.h>
using namespace std;
#define INF 300000
#define pb push_back
#define ss second
#define ff first
int m,n,sz[200005],cnt[1000005],i,j,x,y,k,p,D[200005],ans;
bool R[200005];
vector< pair<int,int> > v[200005];
vector<int> remover;
int sizer(int node, int pre=-1){
	sz[node]=1;
	for(pair<int,int> i:v[node])
	if(i.ff!=pre && !R[i.ff]) sz[node]+=sizer(i.ff,node);
	return sz[node];
}
int get_centroid(int node, int pre=-1){
	for(pair<int,int> i:v[node])
	if(i.ff!=pre && !R[i.ff] && sz[i.ff]>n/2) return get_centroid(i.ff,node);
	return node;
}
void dfs(int node, int pre, int depth){
	if(D[node]>k || depth > ans) return;
	cnt[D[node]]=min(cnt[D[node]],depth);
	remover.pb(D[node]);
	for(pair<int,int> i : v[node])
	if(i.ff!=pre && !R[i.ff]){
		D[i.ff]=D[node]+i.ss;
		dfs(i.ff,node,depth+1);
	}
}
void shaa(int node, int pre, int depth){
	if(D[node]>k || depth > ans) return;
	ans=min(ans,depth+cnt[k-D[node]]);
	for(pair<int,int> i : v[node])
	if(i.ff!=pre && !R[i.ff]) shaa(i.ff,node,depth+1);
}
void solve(int node){
	n=sizer(node);
	int C=get_centroid(node);
	R[C]=true;
	cnt[0]=0;
	for(pair<int,int> child : v[C])
	if(!R[child.ff]){
	    D[child.ff]=child.ss;
		dfs(child.ff,C,1);
		shaa(child.ff,C,1);
	}
	for(int i : remover) cnt[i]=INF;
	remover.clear();
	for(pair<int,int> child : v[C])
	if(!R[child.ff]) solve(child.ff);
}
int best_path(int N, int K, int H[][2], int L[])
{
	k=K;
	for(int i=0;i<=k;i++) cnt[i]=INF;
	for(int i=0;i<N-1;i++){
		v[H[i][0]].pb({H[i][1],L[i]});
		v[H[i][1]].pb({H[i][0],L[i]});
	}
	ans=INF;
	solve(1);
	if(ans>N) return -1;
	return ans;
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57