Submission #1147954

#	Time	Username	Problem	Language	Result	Execution time	Memory
1147954		Kodik	Race (IOI11_race)	C++20	100 / 100	405 ms	101360 KiB

race

#include <bits/stdc++.h>
using namespace std;
#define ss second
#define ff first
typedef long long ll;
#define ll ll
using pi = array<ll, 2>;
const ll MOD = 1e9+7;

const int maxn = 2e5 + 1;
vector<pair<int,int>> adj[maxn];
map<ll, ll> info[maxn];
ll dist[maxn], sum[maxn]; 
int N, K;
ll ret;

void precomp(int u, int p, ll c, int h) {
	info[u][c] = h;
	sum[u] = c;
	dist[u] = h;
	for (auto n : adj[u]) {
		if (p == n.ff) { continue; }
		precomp(n.ff, u, c + n.ss, h + 1);
	}
}

void small_to_large_merge(int u, int p) {
	ll target = K + 2 * sum[u];
	for (auto n : adj[u]) {
		if (n.ff == p) { continue; }
		small_to_large_merge(n.ff, u);
		if (info[n.ff].size() > info[u].size()) { swap(info[n.ff], info[u]); }
		for (auto i : info[n.ff]) {
			if (info[u].find(target - i.ff) != info[u].end()) {
				ret = min(ret, info[u][target - i.ff] + i.ss - 2 * dist[u]);
			}
		}
		for (auto i : info[n.ff]) {
			if (info[u].find(i.ff) == info[u].end()) {
				info[u].insert(i);
			} else {
				info[u][i.ff] = min(info[u][i.ff], i.ss);
			}
		}
	}
}




int best_path(int n, int k, int edges[][2], int weights[]) {
	if (k == 1) { return 0; }
	N = n;
	K = k;
	ret = INT_MAX;
	for (int i = 0; i < n - 1; i++) {
		int u = edges[i][0];
		int v = edges[i][1];
		adj[u].push_back(pair<int,int>(v, weights[i]));
		adj[v].push_back(pair<int,int>(u, weights[i]));
	}
	precomp(0, -1, 0, 0);
	small_to_large_merge(0, -1);
	return ret == INT_MAX ? -1 : ret;
}

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