Submission #59610

#	Time	Username	Problem	Language	Result	Execution time	Memory
59610		spencercompton	Dreaming (IOI13_dreaming)	C++17	100 / 100	267 ms	28572 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
vector<int> adj[100000];
vector<int> adjw[100000];
int sub[100000];
bool v[100000];
pair<int, int> dfs3(int now, int from){
	pair<int, int> ret = make_pair(0,now);
	for(int i = 0; i<adj[now].size(); i++){
		int to = adj[now][i];
		if(to==from){
			continue;
		}
		pair<int, int> got = dfs3(to,now);
		got.first += adjw[now][i];
		ret = max(ret,got);
	}
	return ret;
}
int dfs1(int now, int from){
	v[now] = true;
	sub[now] = 0;
	for(int i = 0; i<adj[now].size(); i++){
		int to = adj[now][i];
		if(to==from){
			continue;
		}
		sub[now] = max(sub[now],adjw[now][i] + dfs1(to, now));
	}
	return sub[now];
}
int dfs2(int now, int from, int above){
	int ret = 1000000007;
	vector<pair<int, int> > li;
	//deep, loc
	for(int i = 0; i<adj[now].size(); i++){
		int to = adj[now][i];
		if(to==from){
			continue;
		}
		li.push_back(make_pair(sub[to]+adjw[now][i],i));
	}
	if(li.size()==0){
		return above;
	}
	int maxi = 0;
	for(int i = 1; i<li.size(); i++){
		if(li[i].first > li[maxi].first){
			maxi = i;
		}
	}
	ret = min(ret, max(above,li[maxi].first));
	int ind = li[maxi].second;
	for(int i = 0; i<li.size(); i++){
		if(i==maxi){
			continue;
		}
		above = max(above,li[i].first);
	}
	above += adjw[now][ind];
	ret = min(ret, dfs2(adj[now][ind],now,above));
	return ret;
}
int travelTime(int n, int m, int l, int a[], int b[], int t[]) {
	for(int i = 0; i<m; i++){
		adj[a[i]].push_back(b[i]);
		adj[b[i]].push_back(a[i]);
		adjw[a[i]].push_back(t[i]);
		adjw[b[i]].push_back(t[i]);
	}
	for(int i = 0; i<n; i++){
		v[i] = false;
	}
	vector<int> all;
	int ans = 0;
	for(int i = 0; i<n; i++){
		if(adj[i].size()==0){
			assert(!v[i]);
			v[i] = true;
			all.push_back(0);
		}
		if(v[i]){
			continue;
		}
		int diam = dfs3(dfs3(i,-1).second,-1).first;
		ans = max(ans,diam);
		dfs1(i,-1);
		all.push_back(dfs2(i,-1,0));
	}
	for(int i = 0; i<n; i++){
		assert(v[i]);
	}
	sort(all.begin(),all.end());
	if(all.size()>0){
		ans = max(ans,all[all.size()-1]);
	}
	if(all.size()>1){
		ans = max(ans,all[all.size()-1] + all[all.size()-2] + l);
	}
	if(all.size()>2){
		ans = max(ans,all[all.size()-3] + all[all.size()-2] + l + l);
	}
	return ans;
}

Compilation message (stderr)

dreaming.cpp: In function 'std::pair<int, int> dfs3(int, int)':
dreaming.cpp:10:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i<adj[now].size(); i++){
                 ~^~~~~~~~~~~~~~~~
dreaming.cpp: In function 'int dfs1(int, int)':
dreaming.cpp:24:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i<adj[now].size(); i++){
                 ~^~~~~~~~~~~~~~~~
dreaming.cpp: In function 'int dfs2(int, int, int)':
dreaming.cpp:37:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i<adj[now].size(); i++){
                 ~^~~~~~~~~~~~~~~~
dreaming.cpp:48:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 1; i<li.size(); i++){
                 ~^~~~~~~~~~
dreaming.cpp:55:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i<li.size(); i++){
                 ~^~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23