Submission #1236049

#	Time	Username	Problem	Language	Result	Execution time	Memory
1236049		allin27x	Race (IOI11_race)	C++17	100 / 100	686 ms	83008 KiB

race

#include <bits/stdc++.h>
using namespace std;
#define ll __int128
const int mod = 1e9+7;
#define forn(i,n) for(int i=0; i<n; i++)
#define readv(a,n) vector<int>a(n);forn(i,n)cin>>a[i];
#define readvv(a,n,m) vector<vector<int>> a(n,vector<int>(m));forn(i,n)forn(j,m)cin>>a[i][j];
#define all(a) a.begin(), a.end()
#define _max(x,y) x = max(x,y)
#define _min(x,y) x = min(x,y)
// #define f first
// #define s second

const int MAXN = 2e5+5;
const int MAXM = 1e6+5;
vector<pair<int,int>> adj[MAXN];
int sbt[MAXN];
vector<int> ch[MAXN];
vector<pair<int,int>> inf[MAXN];
int pn[MAXM];
int rem[MAXN];
int mk[MAXN];
int par[MAXN];
void dfs(int i, int p) {
	sbt[i] = 1;
	for (auto [c, w]: adj[i]) {
		if (c==p || rem[c]) continue;
		dfs(c, i);
		sbt[i] += sbt[c];
	}
}

int ctd(int i, int p, int sz) {
	for (auto [c,w] : adj[i]) {
		if (c==p || rem[c]) continue;
		if (2*sbt[c] > sz) return ctd(c, i, sz);
	}
	return i;
}


void calc(int i, int p, int dsw, int dse, int tp) {
	if (dsw >= MAXM) dsw = MAXM;
	if (i!=p) inf[tp]. push_back({dsw, dse});
	for (auto [c,w]: adj[i]) {
		if (c==p || rem[c]) continue;
		calc(c, i, dsw+w, dse+1, tp);
	}
}

int build(int i) {
	dfs(i, 0);
	int x = ctd(i, i, sbt[i]);
	rem[x] = 1;
	for (auto [c,w] : adj[x]) {
		if (rem[c]) continue;
		ch[x].push_back(build(c));
		par[ch[x].back()] = x;
	}
	return x;
}

int k;
int ans = MAXM;
void solve(int i) {
	inf[i].clear();
	rem[i] = 1;
	for (auto [c,w]:adj[i]) {
		if (rem[c]) continue;
		int tp = c;
		while (par[tp] != i) tp = par[tp];
		calc(c, i, w, 1, tp);
	}
	for (int c: ch[i]) {
		for (auto [dsw, dse]: inf[c]) {
			if (dsw >= MAXM) continue;
			pn[dsw] = MAXM;
			if (dsw <= k) pn[k-dsw] = MAXM;
		}
	}
	pn[0] = 0;
	for (int c: ch[i]) {
		for (auto [dsw, dse]: inf[c]) {
			if (dsw > k) continue;
			ans = min(ans, pn[k-dsw] + dse);
		}
		for (auto[dsw, dse]: inf[c]) {
			if (dsw > k) continue;
			pn[dsw] = min(pn[dsw], dse);
		}
	}
	for (int c: ch[i]) solve(c);
}

int best_path(int N, int K, int H[][2], int L[])
{
	k = K;
	for (int i=0; i<N-1; i++) {
		H[i][0] ++; H[i][1] ++;
		adj[H[i][0]].push_back({H[i][1], L[i]});
		adj[H[i][1]].push_back({H[i][0], L[i]});
	}
	int centr = build(1);
	for (int i=0; i<N+3; i++) rem[i] = 0;
	solve(centr);
	if (ans < MAXM)return ans;
	return -1;
}

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