# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
396720 | JerryLiu06 | Race (IOI11_race) | C++11 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
#include "race.h"
using namespace std;
using ll = long long;
using db = long double;
using str = string;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
#define mp make_pair
#define f first
#define s second
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define sor(x) sort(all(x))
#define ft front()
#define bk back()
#define pb push_back
#define pf push_front
#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 EACH(a, x) for (auto& a : x)
const int MOD = 1e9 + 7;
const int MX = 2e5 + 5;
const ll INF = 1e18;
int N, K, ans = MOD; vpi adj[200010]; int sub[200010]; bool vis[200010]; unordered_map<int, int> cur;
void update(int K, int V) { if (!cur.count(K)) cur[K] = MOD; cur[K] = min(cur[K], V); }
int getVal(int K) { if (!cur.count(K)) return MOD; return cur[K]; }
void DFS1(int X, int P) {
sub[X] = 1; EACH(Y, adj[X]) if (Y.f != P && !vis[Y.f]) { DFS1(Y.f, X); sub[X] += sub[Y.f]; }
}
int getCent(int X, int P, int S) {
EACH(Y, adj[X]) if (Y.f != P && !vis[Y.f] && sub[Y.f] > S / 2) return getCent(Y.f, X, S); return X;
}
void DFS2(int X, int P, bool upd, int dist, int depth) {
if (dist > K) return ; if (upd) update(dist, depth); else ans = min(ans, getVal(K - dist) + depth);
EACH(Y, adj[X]) if (Y.f != P && !vis[Y.f]) DFS2(Y.f, X, upd, dist + Y.s, depth + 1);
}
void decomp(int X, int P) {
DFS1(X, 0); int C = getCent(X, 0, sub[X]); vis[C] = true; cur[0] = 0;
EACH(Y, adj[C]) if (Y.f != P && !vis[Y.f]) { DFS2(Y.f, C, false, Y.s, 1); DFS2(Y.f, C, true, Y.s, 1); }
cur.clear(); EACH(Y, adj[C]) if (Y.f = P && !vis[Y.f]) decomp(Y.f, X);
}
int best_path(int _N, int _K, int H[][2], int L[]) {
N = _N; K = _K; FOR(i, 0, N - 1) {
int A = H[i][0] + 1; int B = H[i][1] + 1;
adj[A].pb({B, L[i]}), adj[B].pb({A, L[i]});
}
decomp(1); return (ans == MOD ? -1 : ans);
}