| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1030420 | vjudge1 | Fun Tour (APIO20_fun) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#define LOCAL
#ifndef LOCAL
#include "fun.h"
#endif
#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
vector<int> createFunTour(int N, int Q);
#include <cassert>
#include <cstdio>
#include <algorithm>
#include <string>
#include <vector>
static void wrongAnswer(std::string message) {
printf("WA: %s\n", message.c_str());
exit(0);
}
namespace tree_helper {
static int N;
static int logN;
static std::vector<std::vector<int>> parent;
static std::vector<int> depth;
static std::vector<int> subtree_size;
static void dfs(
const std::vector<std::vector<int>>& adj_list,
int current_node, int parent_node) {
parent[0][current_node] = parent_node;
subtree_size[current_node] = 1;
for (int i = 0; i < static_cast<int>(adj_list[current_node].size()); ++i) {
const int next_node = adj_list[current_node][i];
if (next_node != parent_node) {
depth[next_node] = depth[current_node] + 1;
dfs(adj_list, next_node, current_node);
subtree_size[current_node] += subtree_size[next_node];
}
}
}
static void initializeTree(const std::vector<std::vector<int>>& adj_list) {
N = static_cast<int>(adj_list.size());
depth = std::vector<int>(N, 0);
subtree_size = std::vector<int>(N, 0);
for (logN = 0; (1 << logN) < N; ++logN) {}
parent = std::vector<std::vector<int>>(logN, std::vector<int>(N, 0));
dfs(adj_list, 0, 0);
for (int i = 1; i < logN; ++i) {
for (int j = 0; j < N; ++j) {
parent[i][j] = parent[i - 1][parent[i - 1][j]];
}
}
}
static int getLowestCommonAncestor(int X, int Y) {
if (depth[X] < depth[Y]) {
std::swap(X, Y);
}
for (int i = logN - 1; i >= 0; --i) {
if (depth[parent[i][X]] >= depth[Y]) {
X = parent[i][X];
}
}
if (X == Y) {
return X;
}
for (int i = logN - 1; i >= 0; --i) {
if (parent[i][X] != parent[i][Y]) {
X = parent[i][X];
Y = parent[i][Y];
}
}
return parent[0][X];
}
static int getDistance(int X, int Y) {
return depth[X] + depth[Y] - 2 * depth[getLowestCommonAncestor(X, Y)];
}
static int attractionsBehind(int X, int Y) {
if (X == Y) {
return N;
}
for (int i = logN - 1; i >= 0; --i) {
if (depth[parent[i][X]] > depth[Y]) {
X = parent[i][X];
}
}
if (Y == parent[0][X]) {
return N - subtree_size[X];
}
return subtree_size[Y];
}
static void checkFunTour(const std::vector<int>& fun_tour) {
if (static_cast<int>(fun_tour.size()) != N) {
wrongAnswer("Invalid size");
}
std::vector<bool> visited_attractions(N, false);
for (int i = 0; i < N; ++i) {
if (fun_tour[i] < 0 || fun_tour[i] >= N) {
wrongAnswer("Invalid index");
}
if (visited_attractions[fun_tour[i]]) {
wrongAnswer("Repeated index");
}
visited_attractions[fun_tour[i]] = true;
}
int last_travel_time = getDistance(fun_tour[0], fun_tour[1]);
for (int i = 2; i < N; ++i) {
int travel_time = getDistance(fun_tour[i - 1], fun_tour[i]);
if (travel_time > last_travel_time) {
wrongAnswer("Tour is not fun");
}
last_travel_time = travel_time;
}
}
} // namespace tree_helper
static int N, Q;
int hoursRequired(int X, int Y) {
if (--Q < 0) {
wrongAnswer("Too many queries");
}
if (X < 0 || X >= N || Y < 0 || Y >= N) {
wrongAnswer("Invalid index");
}
return tree_helper::getDistance(X, Y);
}
int attractionsBehind(int X, int Y) {
if (--Q < 0) {
wrongAnswer("Too many queries");
}
if (X < 0 || X >= N || Y < 0 || Y >= N) {
wrongAnswer("Invalid index");
}
return tree_helper::attractionsBehind(X, Y);
}
int main() {
assert(2 == scanf("%d %d", &N, &Q));
std::vector<std::vector<int>> adj_list(N);
for (int i = 0; i < N - 1; ++i) {
int A, B;
assert(2 == scanf("%d %d", &A, &B));
adj_list[A].push_back(B);
adj_list[B].push_back(A);
}
tree_helper::initializeTree(adj_list);
std::vector<int> fun_tour = createFunTour(N, Q);
tree_helper::checkFunTour(fun_tour);
for (int i = 0; i < N; ++i) {
printf("%d%c", fun_tour[i], " \n"[i == N - 1]);
}
return 0;
}
#endif
using namespace std;
vector<int>ans;
void makedouble(vector<pair<int,int>>a,vector<pair<int,int>>b){
sort(a.begin(),a.end());
sort(b.begin(),b.end());
while(a.size()||b.size()){
ans.push_back(b.back().second);
b.pop_back();
swap(a,b);
}
}
vector<pair<int,int>>concat(vector<pair<int,int>> a,vector<pair<int,int>> b){
for(auto i:b)
a.push_back(i);
return a;
}
void stuff(vector<pair<int,int>>why[3],int a,int b,int c,int k){
if(k-a) makedouble(concat(why[b],why[c]),why[a]);
else makedouble(why[a],concat(why[b],why[c]));
}
vector<int> createFunTour(int N, int Q) {
if(N==2) return{0,1};
pair<int,int>centroid{N,0};
for(int i=1;i<N;i++) {
int k=attractionsBehind(0,i);
if(k>=(N+1)/2)
centroid=min(centroid,{k,i});
}
int k=centroid.second;
vector<int>subtreez;
vector<pair<int,int>> why[3];
for(int i=0;i<N;i++){
if(i==k) continue;
int C=hoursRequired(k,i);
if(!subtreez.size()){
subtreez.push_back(i);
why[0].push_back({C,i});
} else if(subtreez.size()==1){
if(why[0][0].first+C-hoursRequired(why[0][0].second,i))
why[0].push_back({C,i});
else subtreez.push_back(i),why[1].push_back({C,i});
} else {
if(why[0][0].first+C-hoursRequired(why[0][0].second,i))
why[0].push_back({C,i});
else if(why[1][0].first+C-hoursRequired(why[1][0].second,i))
why[1].push_back({C,i});
else why[2].push_back({C,i});
}
}
sort(why[0].begin(),why[0].end());
sort(why[1].begin(),why[1].end());
sort(why[2].begin(),why[2].end());
sort(why,why+3,[](vector<pair<int,int>>&a,vector<pair<int,int>>&b){
return a.size()>b.size();
});
if(why[2].empty()){
makedouble(why[1],why[0]);
} else if(why[0].size()>=why[1].size()+why[2].size()){
makedouble(concat(why[1],why[2]), why[0]);
} else {
sort(why,why+3,[](vector<pair<int,int>>&a,vector<pair<int,int>>&b){
return a.back()>b.back();
});
int prv=0;
ans.push_back(why[0].back().second);
why[0].pop_back();
while(1){
int A=why[0].size(),B=why[1].size(),C=why[2].size();
if(A+B==C){
stuff(why,2,0,1,prv);
break;
} else if (A+C==B){
stuff(why,1,2,0,prv);
break;
} else if (B+C==A){
stuff(why,0,1,2,prv);
break;
}
pair<int,int>s{0,0};
for(int i=0;i<3;i++)
if(i-prv)s=max(s,{why[i].back().first,i});
prv=s.second;
ans.push_back(why[prv].back().second);
why[prv].pop_back();
}
}
ans.push_back(k);
return ans;
}