제출 #466568

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
466568		dattranxxx	경주 (Race) (IOI11_race)	C++11	0 / 100	8 ms	12044 KiB

race

#include "race.h"
/*
 * Author :  shora
 */
#include <bits/stdc++.h>
#define print(_v) for (auto &_ : _v) {cerr << _ << ' ';} cerr << endl;
using namespace std;
using ll = long long;
const int oo = 1e9;
const int N = 5e5, K = 1e6;
struct C {
	int v, w;
	C(int v, int w): v(v), w(w) {}
};
vector<C> G[N];
int vis[N], size[N], f[K + 1], dep[N];
int k;
int res = oo;
void find_size(int u, int e = -1) {
	size[u] = 1;
	for (C& c : G[u]) if (c.v != e && !vis[c.v]) {
		find_size(c.v, u);
		size[u] += size[c.v];
	}
}
int centroid(int s, int u, int e = -1) {
	for (C& c : G[u]) if (c.v != e && !vis[c.v])
		if (size[c.v] > s / 2)
			return centroid(s, c.v, u);
	return u;
}
void dfs(int u, int e = -1, ll dis = 0) {
	if (k < dis) 
		return;
	if (e != -1)
		dep[u] = dep[e] + 1;
	if (f[k - dis] != oo) 
		res = min(res, f[k - dis] + dep[u]); 
	for (C& c : G[u]) if (c.v != e && !vis[c.v]) {
		dfs(c.v, u, dis + c.w);
	}
	f[dis] = min(f[dis], dep[u]);
}
void clear(int u, int e = -1, ll dis = 0) {
	if (k < dis)
		return;
	dep[u] = 0;
	for (C& c : G[u]) if (c.v != e && !vis[c.v]) {
		clear(c.v, u, dis + c.w);
	}
	f[dis] = oo;
}
void solve(int u) {
	find_size(u);
	u = centroid(size[u], u);
	vis[u] = 1;
	dfs(u); clear(u);
	for (C& c : G[u]) if (!vis[c.v])
		solve(c.v);
}
int best_path(int n, int K, int H[][2], int L[]) {
	k = K;
	for (int i = 0, u, v, w; i < n-1; ++i) {
		u = H[i][0]; v = H[i][1]; w = L[i];
		G[u].push_back(C(v, w));
		G[v].push_back(C{u, w});
	}
	for (int i = 1; i <= k; ++i)
		f[i] = oo;
	res = oo;
	solve(0);
  return res == oo ? -1 : res;
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57