Submission #1277351

#	Time	Username	Problem	Language	Result	Execution time	Memory
1277351		crispxx	Dreaming (IOI13_dreaming)	C++20	100 / 100	78 ms	25284 KiB

dreaming

#include "dreaming.h"

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

#define all(x) x.begin(), x.end()
#define pb push_back
#define ar array

template <typename A, typename B>
bool chmin(A &a, const B &b) {
	if(a > b) {
		return a = b, true;
	}
	return false;
}

template <typename A, typename B>
bool chmax(A &a, const B &b) {
	if(a < b) {
		return a = b, true;
	}
	return false;
}

int travelTime(int n, int m, int l, int A[], int B[], int T[]) {
	vector<vector<ar<int, 2>>> adj(n);
	
	// cout << n << ' ' << m << ' ' << l << endl;
	
	for(int i = 0; i < m; i++) {
		// cout << i << endl;
		adj[A[i]].pb({B[i], T[i]});
		adj[B[i]].pb({A[i], T[i]});
	}
	
	vector<int> used(n), mx(n), mx2(n), d(n);
	
	auto dfs = [&](auto &&self, int v) -> void {
		used[v] = true;
		mx[v] = d[v];
		for(auto [to, w] : adj[v]) {
			if(used[to]) continue;
			d[to] = d[v] + w;
			self(self, to);
			chmax(mx2[v], mx[to]);
			if(mx2[v] > mx[v]) swap(mx2[v], mx[v]);
		}
	};
	
	for(int i = 0; i < n; i++) {
		// cout << i << endl;
		if(!used[i]) {
			dfs(dfs, i);
		}
	}
	
	fill(all(used), false);
	
	vector<int> mx_root(n);
	
	int mn = 1e9, ver = -1;
	
	auto dfs2 = [&](auto &&self, int v) -> void {
		used[v] = true;
		
		int res = max(mx_root[v], mx[v] - d[v]);
		
		if(chmin(mn, res)) ver = v;
		
		for(auto [to, w] : adj[v]) {
			if(used[to]) continue;
			
			chmax(mx_root[to], mx_root[v] + w);
			
			int val = mx[v];
			if(val == mx[to]) val = mx2[v];
			
			chmax(mx_root[to], (val - d[v]) + w);
			
			self(self, to);
		}
		
	};
	
	auto nadj = adj;
	
	vector<ar<int, 2>> b;
	
	for(int i = 0; i < n; i++) {
		if(!used[i]) {
			mn = 1e9;
			ver = -1;
			dfs2(dfs2, i);
			b.pb({mn, ver});
		}
	}
	
	sort(all(b), greater<>());
	
	for(int i = 1; i < (int)b.size(); i++) {
		nadj[b[0][1]].pb({b[i][1], l});
		nadj[b[i][1]].pb({b[0][1], l});
	}
	
	fill(all(mx), 0);
	fill(all(mx2), 0);
	fill(all(d), 0);
	fill(all(mx_root), 0);
	fill(all(used), false);
	
	int ans = 0;
	
	auto ndfs = [&](auto &&self, int v) -> void {
		used[v] = true;
		mx[v] = d[v];
		for(auto [to, w] : nadj[v]) {
			if(used[to]) continue;
			d[to] = d[v] + w;
			self(self, to);
			chmax(mx2[v], mx[to]);
			if(mx2[v] > mx[v]) swap(mx2[v], mx[v]);
		}
	};
	
	ndfs(ndfs, 0);
	
	fill(all(used), false);
	
	auto ndfs2 = [&](auto &&self, int v) -> void {
		used[v] = true;
		
		int res = max(mx_root[v], mx[v] - d[v]);
		
		chmax(ans, res);
		
		for(auto [to, w] : nadj[v]) {
			if(used[to]) continue;
			
			chmax(mx_root[to], mx_root[v] + w);
			
			int val = mx[v];
			if(val == mx[to]) val = mx2[v];
			
			chmax(mx_root[to], (val - d[v]) + w);
			
			self(self, to);
		}
		
	};
	
	ndfs2(ndfs2, 0);
	
	return ans;
}

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