Submission #1198726

#	Time	Username	Problem	Language	Result	Execution time	Memory
1198726		aguss	Highway Tolls (IOI18_highway)	C++20	6 / 100	253 ms	327680 KiB

highway

#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define dbg(x) cerr << #x << ": " << x << "\n";
#define dbgv(x) cerr << #x << ": "; for(auto &i : x) cout << i << ' '; cout << "\n";
vector<vector<pair<int, int>>> arr;
vector<int> depth, path;
void dfs(int node, int prev = -1){
	for(const auto &i : arr[node]){
		if(i.first == prev) continue;
		depth[i.first] = depth[node] + 1;
		path.push_back(i.second);
		dfs(i.first, node);
	}
}

pair<int, int> idk(ll dis1, ll dis2, int A, int B){
	int x, y;
	y = (dis2 - dis1) / (B - A);
	x = dis1 / A - y;
	return {x, y};
}

void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
	arr.assign(N, vector<pair<int, int>>());
	depth.assign(N, 0);
	for(int i = 0; i < (int)U.size(); i++){
		arr[U[i]].push_back({V[i], i});
		arr[V[i]].push_back({U[i], i});
	}
	int root = 0;
	for(int i = 0; i < N; i++){
		if(arr[i].size() == 1){
			root = i;
			break;
		}
	}
	dfs(root);
	//dbgv(path);
	//dbgv(depth);
	vector<int> vec(N - 1, 0);
	int s = 0, t = 0, l = 0, r = N - 1, m = (l + r) / 2;
	long long dis1 = ask(vec), dis2 = 0;
	while(l + 1 < r){
		m = (l + r) / 2;
		for(int i = l; i < m; i++){
			vec[path[i]] = 1;
		}
		dis2 = ask(vec);
		if(dis2 / B == dis1 / A){
			vec.assign(N - 1, 0);
			r = m;
			continue;
		}
		if(dis2 == dis1){
			l = m;
			continue;
		}
		break;
	}
	pair<int, int> ans = idk(dis1, dis2, A, B);
	int disl = ans.second, disr = ans.first;
	//dbg(m);
	//dbg(disl);
	//dbg(disr);
	//dbg(dis1);
	//dbg(dis2);
	for(int i = 0; i < N; i++){
		if(depth[i] == m + disr){
			s = i;
			continue;
		}
		if(depth[i] == m - disl){
			t = i;
			continue;
		}
	}
	answer(s, t);
}

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