Submission #705713

#	Time	Username	Problem	Language	Result	Execution time	Memory
705713		khshg	Race (IOI11_race)	C++14	100 / 100	485 ms	36140 KiB

race

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

using ll = long long;
using ld = long double;
using str = string;

using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<ld, ld>;
#define mp make_pair
#define ff first
#define ss second

template<class T> using V = vector<T>;
#define arr array
using vi = V<int>;
using vb = V<bool>;
using vl = V<ll>;
using vd = V<ld>;
using vs = V<str>;
using vpi = V<pi>;
using vpl = V<pl>;
using vpd = V<pd>;

#define sz(x) (int)((x).size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) (x).rbegin(), (x).rend()
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define pb push_back
#define eb emplace_back
#define ft front()
#define bk back()

#define lb lower_bound
#define ub upper_bound

#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for(int i = (b) - 1; i >= (a); --i)
#define R0F(i, a) ROF(i, 0, a)
#define rep(a) F0R(_, a)
#define trav(a, x) for(auto& a : x)

template<class T> bool ckmin(T& a, const T& b) { return (b < a ? a = b, 1 : 0); }
template<class T> bool ckmax(T& a, const T& b) { return (b > a ? a = b, 1 : 0); }

int N, K, ans;
vi ssz, kp;
vb vis;
V<vpi> adj;

int dfs0(int s, int p = -1) {
	ssz[s] = 1;
	trav(u, adj[s]) {
		if(u.ff != p && !vis[u.ff]) ssz[s] += dfs0(u.ff, s);
	}
	return ssz[s];
}

int cent(int s, int des, int p = -1) {
	trav(u, adj[s]) {
		if(u.ff != p && !vis[u.ff] && 2 * ssz[u.ff] > des) return cent(u.ff, des, s);
	}
	return s;
}

void dfs1(int s, pi D, int c, int p = -1) {
	if(D.ff > K) return;
	if(c == 0) {
		ckmin(ans, D.ss + kp[K - D.ff]);
	} else if(c == 1) {
		ckmin(kp[D.ff], D.ss);
	} else {
		kp[D.ff] = 0x3f3f3f3f;
	}
	trav(u, adj[s]) {
		if(u.ff != p && !vis[u.ff]) dfs1(u.ff, mp(D.ff + u.ss, D.ss + 1), c, s);
	}
}

void cent_deco(int s = 0) {
	s = cent(s, dfs0(s));
	vis[s] = 1;
	kp[0] = 0;
	trav(u, adj[s]) {
		if(vis[u.ff]) continue;
		dfs1(u.ff, mp(u.ss, 1), 0);
		dfs1(u.ff, mp(u.ss, 1), 1);
	}
	trav(u, adj[s]) {
		if(vis[u.ff]) continue;
		dfs1(u.ff, mp(u.ss, 1), 2);
	}
	trav(u, adj[s]) {
		if(vis[u.ff]) continue;
		cent_deco(u.ff);
	}
}

int best_path(int _N, int _K, int e[][2], int w[]) {
	N = _N; K = _K;
	vis.rsz(N);
	adj.rsz(N);
	ssz.rsz(N);
	ans = 0x3f3f3f3f;
	kp = vi(K + 1, ans);
	F0R(i, N - 1) {
		adj[e[i][0]].eb(e[i][1], w[i]);
		adj[e[i][1]].eb(e[i][0], w[i]);
	}
	cent_deco();
	if(ans == 0x3f3f3f3f) ans = -1;
	return ans;
}

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