# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1035960 | andrewp | Race (IOI11_race) | C++14 | 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 "race.h"
#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
using ll = int64_t;
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define dbg(x) cerr << #x << ": " << x << '\n';
const int N = 2e5 + 20, INF = 1e9 + 20;
int n, price[N], dep[N];
int k, ans = INF;
vector<pii> g[N];
map<int, int> mp[N];
void build(int x, int par) {
for (auto u : g[x]) {
if (u.first != par) {
build(u.first, x);
dep[u.first] = dep[x] + 1;
price[u.first] = price[x] + u.second;
}
}
}
void dfs(int x, int par) {
mp[x][price[x]] = dep[x];
for (auto u : g[x]) {
if (u.first != par) {
dfs(u.first, x);
if (mp[u.first].size() > mp[x].size()) {
swap(mp[u.first], mp[x]);
}
int calc = 2 * price[x] + k;
for (auto add : mp[u.first]) {
calc -= add.first;
if (mp[x].count(calc)) {
ans = min(ans, mp[x][calc] + u.second - 2 * dep[x]);
}
calc += add.first;
}
for (auto add : mp[u.first]) {
if (mp[x].count(add.first)) {
mp[x][add.first] = min(mp[x][add.first], add.second);
} else {
mp[x][add.first] = add.second;
}
}
if (mp[x][calc - price[x]]) {
ans = min(ans, mp[x][calc - price[x]] - dep[x]);
}
}
}
}
int best_path(int NN, int K, int H[][2], int LEN[]) {
n = NN, k = K;
for (int i = 0; i < n - 1; i++) {
int u = H[i][0];
int v = H[i][1];
int w = LEN[i];
g[u].push_back({v, w});
g[v].push_back({u, w});
}
dep[0] = 0, price[0] = 0;
build(0, -1);
dfs(0, -1);
return ans;
}
int32_t main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
cout.tie(nullptr); cerr.tie(nullptr);
int NN, K;
cin >> NN >> K;
int H[NN][2], LEN[NN];
for (int i = 0; i < NN - 1; i++) {
cin >> H[i][0] >> H[i][1];
}
for (int i = 0; i < NN - 1; i++) {
cin >> LEN[i];
}
int ans = best_path(NN, K, H, LEN);
cout << "Solution: " << (ans == INF ? -1 : ans - 1) << '\n';
}