Submission #1064210

#	Time	Username	Problem	Language	Result	Execution time	Memory
1064210		kkkkkkkk	Race (IOI11_race)	C++17	100 / 100	657 ms	41696 KiB

race

#include <bits/stdc++.h>

using namespace std;

vector<pair<int,int> > G[200005];
int is_removed[200005], subtree_size[200005];
map<int,int> cekori;
int k;
int rez;

void get_subtree_size(int teme, int parent) {
	subtree_size[teme]=1;
	for (auto [next, dist]:G[teme]){
		if (next==parent||is_removed[next]) continue;
		get_subtree_size(next, teme);
		subtree_size[teme]+=subtree_size[next];
	}
}

int find_centroid(int teme, int parent, int nodes){
	for (auto [next, dist]:G[teme]){
		if (next==parent||is_removed[next]) continue;
		if (subtree_size[next]>=nodes/2)
            return find_centroid(next, teme, nodes);
	}
	return teme;
}

void check(int teme, int parent, int dolz, int depth){
	if (dolz>k) return ;
	if (cekori.find(k-dolz)!=cekori.end())
        rez=min(rez, cekori[k-dolz]+depth);
	for (auto [next, dist]:G[teme]){
		if (next==parent||is_removed[next]) continue;
		check(next, teme, dolz+dist, depth+1);
	}
}

void build(int teme, int parent, int dolz, int depth){
	if (dolz>k) return ;
	if (cekori.find(dolz)==cekori.end())
        cekori[dolz]=depth;
	else cekori[dolz]=min(cekori[dolz], depth);
	for (auto [next, dist]:G[teme]){
		if (next==parent||is_removed[next]) continue;
		build(next, teme, dolz+dist, depth+1);
	}
}

void build_centroid_decomp(int teme) {
	get_subtree_size(teme, -1);
	int centroid=find_centroid(teme, -1, subtree_size[teme]);
	cekori[0]=0;
	for (auto [next, dist]:G[centroid]) {
		if (is_removed[next]) continue;
		check(next, centroid, dist, 1);
		build(next, centroid, dist, 1);
	}
	cekori.clear();
	is_removed[centroid]=1;
	for (auto [next, dist]:G[centroid]) {
		if (is_removed[next]) continue;
		build_centroid_decomp(next);
	}
}

int best_path(int N, int K, int H[][2], int L[]) {
	k=K;
	for (int i=0;i<N-1;i++) {
		G[H[i][0]].push_back({H[i][1], L[i]});
		G[H[i][1]].push_back({H[i][0], L[i]});
	}
	rez=INT_MAX;
	build_centroid_decomp(0);
	if (rez==INT_MAX) rez=-1;
	return rez;
}

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