| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 98646 | PeppaPig | 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>
#define long long long
#define pii pair<int, int>
#define x first
#define y second
using namespace std;
const int N = 2e5 + 5;
int n, k, ans = INT_MAX;
int hv[N], in[N], out[N], pos[N], par[N], dep[N];
long d[N];
map<long, int> mp;
vector<pii> g[N];
int gethv(int u, int v) {
static int idx = 0;
int sz = 1; pii ret(0, -1);
par[u] = p, in[u] = ++idx, pos[idx] = u;
for(pii v : g[u]) if(v.x != p) {
d[v.x] = d[u] + v.y;
dep[v.x] = dep[u] + 1;
int z = gethv(v.x, u);
sz += z, ret = max(ret, (z, v.x));
}
out[u] = idx, hv[u] = ret.y;
return sz;
}
void add(int u) {
if(!mp.count(d[u])) mp[d[u]] = dep[u];
else mp[d[u]] = min(mp[d[u]], dep[u]);
}
void getans(int u, int lca) {
long ret = k - d[u] + 2*d[lca];
if(mp.count(ret)) {
int z = mp[ret] + dep[u] - 2*dep[lca];
ans = min(ans, z);
}
}
void dfs(int u, int p, bool keep) {
for(pii v : g[u]) if(v.x != p && v.x != hv[u]) dfs(v.x, u, 0);
if(hv[u] != -1) dfs(hv[u], u, 1);
getans(u, u), add(u);
for(pii v : g[u]) if(v.x != p && v.x != hv[u]) {
for(int i = in[v.x]; i <= out[v.x]; i++) getans(pos[i], u);
for(int i = in[v.x]; i <= out[v.x]; i++) add(pos[i], u);
}
if(!keep) mp.clear();
}
int best_path(int N, int K, int H[][2], int L[]) {
n = N, k = K;
for(int i = 0; i < N - 1; i++) {
g[H[i][0]].emplace_back(H[i][1], L[i]);
g[H[i][1]].emplace_back(H[i][0], L[i]);
}
gethv(0, 0);
dfs(0, 0, 1);
return ans;
}