| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 138136 | Mahmoud_Adel | Mergers (JOI19_mergers) | 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 <bits/stdc++.h>
using namespace std;
#define f first
#define s second
typedef long long ll;
const int N = 5e5+5;
int n, m, ans, cur, s[N], dep[N], sp[N][20], sub[N], ret[N], mark[N], deg[N];
vector<int> adj[N], vec[N];
void pre(int u, int p)
{
sub[u] = 1;
dep[u] = dep[p]+1;
sp[u][0] = p;
for(int i=1; i<20; i++) sp[u][i] = sp[sp[u][i-1]][i-1];
for(int v : adj[u]) if(v != p) pre(v, u), sub[u] += sub[v];
}
int equate(int u, int v)
{
int c = dep[u]-dep[v];
for(int i=0; i<20; i++) if(c & (1<<i)) u = sp[u][i];
return u;
}
int LCA(int u, int v)
{
if(dep[u] < dep[v]) swap(u, v);
u = equate(u, v);
if(u == v) return u;
for(int i=19; i>=0; i--) if(sp[u][i] != sp[v][i]) u = sp[u][i], v = sp[v][i];
return sp[u][0];
}
void calc(int u, int p)
{
for(auto v : adj[u]) if(v != p) calc(v, u), ret[u] += ret[v];
if(ret[u] == sub[u]) mark[u] = 1;
}
void DFS(int u, int p, int last)
{
for(int v : adj[u]) if(p != v)
{
if(mark[v]), deg[v]++, deg[last]++, DFS(v, u, v);
else DFS(v, u, last);
}
}
int main()
{
scanf("%d %d", &n, &m);
memset(sp, -1, sizeof sp);
for(int i=1, a, b; i<n; i++) scanf("%d %d", &a, &b),
adj[a].push_back(b), adj[b].push_back(a);
for(int i=1; i<=n; i++) scanf("%d", &s[i]), vec[s[i]].push_back(i);
pre(1, 0);
for(int i=1; i<=m; i++)
{
if(vec[i].empty()) continue;
int node = vec[i][0];
for(auto u : vec[i]) node = LCA(node, u);
ret[node] += (int)vec[i].size();
assert(node);
}
calc(1, 0);
DFS(1, 0, 1);
for(int i=1; i<=n; i++) ans += (deg[i]==1);
cout << (ans+1)/2 << endl;
}