제출 #957828

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
957828		Trisanu_Das	Race (IOI11_race)	C++17	100 / 100	406 ms	108624 KiB

race

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb push_back
#define ff first
#define ss second
 
vector<pair<ll, ll> > adj[200005];
map<ll, ll> sum_to_dist[200005];
ll dist[200005], sum[200005];
int N, K;
ll ans;
 
void dfs(int u, int p, ll s, int d) {
	sum_to_dist[u][s] = d;
	sum[u] = s;
	dist[u] = d;
	for (auto v : adj[u]) if (p != v.ff) dfs(v.ff, u, s + v.ss, d + 1);
}
 
void merge_dfs(int u, int p) {
	ll target = K + 2 * sum[u];
	for (auto v : adj[u]) {
		if (v.ff == p) continue;
		merge_dfs(v.ff, u);
		if (sum_to_dist[v.ff].size() > sum_to_dist[u].size()) swap(sum_to_dist[v.ff], sum_to_dist[u]);
		for (auto p : sum_to_dist[v.ff]) if (sum_to_dist[u].find(target - p.ff) != sum_to_dist[u].end()) ans = min(ans, sum_to_dist[u][target - p.ff] + p.ss - 2 * dist[u]);
		for (auto p : sum_to_dist[v.ff]) {
			if (sum_to_dist[u].find(p.ff) == sum_to_dist[u].end()) sum_to_dist[u].insert(p);
			else sum_to_dist[u][p.ff] = min(sum_to_dist[u][p.ff], p.ss);
		}
	}
}
 
int best_path(int n, int k, int h[][2], int l[]) {
	if (k == 1) return 0;
	N = n; K = k; ans = INT_MAX;
	for (int i = 0; i < n - 1; i++) {
		int u = h[i][0], v = h[i][1];
		adj[u].pb(make_pair(v, l[i]));
		adj[v].pb(make_pair(u, l[i]));
	}
	dfs(0, -1, 0, 0);
	merge_dfs(0, -1);
	return ans == INT_MAX ? -1 : ans;
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 22 / 22
• Subtask 4: 57 / 57