Submission #999294

#	Time	Username	Problem	Language	Result	Execution time	Memory
999294		Unforgettablepl	Highway Tolls (IOI18_highway)	C++17	12 / 100	205 ms	262144 KiB

highway

#include <bits/stdc++.h>
using namespace std;

#define all(x) x.begin(),x.end()

long long ask(const std::vector<int> &w);
void answer(int s, int t);

void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
	vector<vector<pair<int,int>>> adj(N);
	for(int i=0;i<U.size();i++){
		adj[U[i]].emplace_back(V[i],i);
		adj[V[i]].emplace_back(U[i],i);
	}
	vector<int> pedge(N);
	vector<int> depth(N);
	function<void(int,int,int,int)> dfs = [&](int x,int p,int dep,int par){
		depth[x]=dep;
		pedge[x]=par;
		for(auto&i:adj[x])if(i.first!=p)dfs(i.first,x,dep+1,i.second);
	};
	dfs(0,-1,0,-1);
	int M = U.size();
	auto base = ask(vector<int>(M));
	auto basedep = base/((long long)A);
	vector<int> sus;
	for(int i=0;i<N;i++)if(depth[i]==basedep)sus.emplace_back(i);
	while(sus.size()>1){
		int mid = (sus.size())/2;
		vector<int> left,right;
		for(int i=0;i<mid;i++)left.emplace_back(sus[i]);
		for(int i=mid;i<sus.size();i++)right.emplace_back(sus[i]);
		vector<int> w(M);
		for(int&i:left)w[pedge[i]]=1;
		auto ans = ask(w);
		if(ans!=base)sus=left;
		else sus=right;
	}
	answer(0, sus[0]);
}

Compilation message (stderr)

highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:11:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |  for(int i=0;i<U.size();i++){
      |              ~^~~~~~~~~
highway.cpp:32:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |   for(int i=mid;i<sus.size();i++)right.emplace_back(sus[i]);
      |                 ~^~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 0 / 6
• Subtask 4: 0 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31