Submission #824490

#	Time	Username	Problem	Language	Result	Execution time	Memory
824490		tomruk	Split the Attractions (IOI19_split)	C++17	40 / 100	98 ms	17516 KiB

split

#include "split.h"
#include <bits/stdc++.h>
#define N 100005
using namespace std;
int par[N];
vector<int> adj[N];
int sub[N];
int n;
int find(int a){
	if(a == par[a])
		return a;
	return par[a] = find(par[a]);
}
bool merge(int a,int b){
	a = find(a);
	b = find(b);
	if(a== b)
		return 0;
	par[a] = b;
	return 1;
}
int dfs1(int v,int pr){
	sub[v] = 1;
	int ret = v;
	for(auto u:adj[v]){
		if(u == pr)continue;
		int tmp = dfs1(u,v);
		sub[v] += sub[u];
		if(sub[u] > n/2){
			ret = tmp;
		}
	}
	return ret;
}
vector<int> res;
int need;
int ban = -1;
void dfs2(int v,int pr,int col){
	if(!need)
		return;
	res[v] = col;
	need--;
	for(auto u:adj[v]){
		if(u == pr || u == ban)continue;
		dfs2(u,v,col);
	}
}
vector<int> find_split(int _n, int a, int b, int c, vector<int> p, vector<int> q){
	n = _n;
	res.assign(n,0);
	for(int i = 0;i<n;i++){
		par[i] = i;
	}
	for(int i = 0;i<p.size();i++){
		if(merge(p[i],q[i])){
			adj[p[i]].push_back(q[i]);
			adj[q[i]].push_back(p[i]);
		}
	}
	int cent = dfs1(0,-1);
	dfs1(cent,-1);
	vector<int> v = {a,b,c};
	vector<int> ord = {0,1,2};
	sort(ord.begin(),ord.end(),[&](int a,int b){
		return v[a] < v[b];
	});
	for(auto u:adj[cent]){
		if(sub[u] >= v[ord[0]]){
			ban = u;
			need = v[ord[0]];
			dfs2(u,cent,1 + ord[0]);
			break;
		}
	}
	if(ban != -1){
		for(int i = 0;i<n;i++){
			if(res[i] == 0)
				res[i] = ord[2] + 1;
		}
		need = v[ord[1]];
		dfs2(cent,-1,ord[1] + 1);
	}
	return res;
}

Compilation message (stderr)

split.cpp: In function 'std::vector<int> find_split(int, int, int, int, std::vector<int>, std::vector<int>)':
split.cpp:54:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |  for(int i = 0;i<p.size();i++){
      |                ~^~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 22 / 22
• Subtask 4: 0 / 24
• Subtask 5: 0 / 36