Submission #890575

#	Time	Username	Problem	Language	Result	Execution time	Memory
890575		oblantis	Race (IOI11_race)	C++17	0 / 100	2 ms	9780 KiB

race

#include <bits/stdc++.h>
#include "race.h"
#define all(v) v.begin(), v.end()
#define pb push_back
#define ss second
#define ff first
#define vt vector
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, int> pdi;
const ll inf = 1e9 + 10000;
const int mod = 1e9+7;
const int maxn = 2e5 + 12;
vector<pii> g[maxn];
int sz[maxn], ans = maxn, k;
bool was[maxn];
void dfs(int v, int pr) {
	sz[v] = 1;
	for(auto i : g[v]) {
		if(!was[i.ff] && i.ff != pr) {
			dfs(i.ff, v);
			sz[v] += sz[i.ff];
		}
	}
}
int fnd(int v, int pr, int n) {
	for(auto i : g[v]) {
		if(!was[i.ff] && i.ff != pr){ 
			if(sz[i.ff] > n / 2) {
				return fnd(i.ff, v, n);
			}
		}
	}
	return v;
}
map<int, int> ok;
vector<pii> upd;
void cnt(int v, int pr, int x, int y) {
	if(x <= k){
		if(ok.find(k - x) != ok.end())ans = min(ans, ok[k - x] + y);
	}
	else x = k + 1;
	sz[v] = 1;
	for(auto i : g[v]) {
		 if(i.ff != pr && !was[i.ff]) {
			cnt(i.ff, v, x + i.ss, y + 1);
			sz[v] += sz[i.ff];
		 }
	}
	upd.pb({x, y});
}
void go(int v, int n) {
	dfs(v, -1);
	int cen = fnd(v, -1, n);
	was[cen] = 1;
	ok.clear();
	ok[0] = 0;
	for(auto i : g[cen]){ 
		if(!was[i.ff]){
			cnt(i.ff, cen, i.ss, 1);
			while(!upd.empty()){
				if(upd.back().ff <= k) {
					if(ok.find(upd.back().ff) == ok.end())ok[upd.back().ff] = upd.back().ss;
					else ok[upd.back().ff] = min(ok[upd.back().ff], upd.back().ss);
				}
				upd.pop_back();
			}
		}
	}
	for(auto i : g[cen]){
		if(!was[i.ff]){
			go(i.ff, sz[i.ff]);
		}
	}
}
int best_path(int n, int K, int h[][2], int l[]){
	k = K;
	for(int i = 0; i < n; i++ ){
		g[h[i][0]].pb({h[i][1], l[i]});
		g[h[i][1]].pb({h[i][0], l[i]});
	}
	if(K == 0)ans = 0;
	go(0, n);
	return (ans == maxn ? -1 : ans);
}

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