Submission #118319

#	Time	Username	Problem	Language	Result	Execution time	Memory
118319		raghav0307	Mergers (JOI19_mergers)	C++14	0 / 100	213 ms	66076 KiB

mergers

/*raghav0307 - Raghav Gupta*/

#include <bits/stdc++.h>
using namespace std;

#define ff first
#define ss second
#define pb push_back
#define fast_io() ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);

typedef long long ll;
typedef pair<int, int> pii;
typedef long double ld;
#define int ll
const int MAXN = 5e5 + 5;

vector<int> graph[MAXN];
vector<int> state[MAXN];

int depth[MAXN];
int parent[MAXN];
set<int> degree[MAXN];

void dfs(int nd, int p, int lvl){
	parent[nd] = p;
	depth[nd] = lvl;
	for(auto x: graph[nd]){
		if(x == p)	continue;
		dfs(x, nd, lvl+1);
	}
}

int color[MAXN];

int find(int x){
	return color[x] == x ? x : color[x] = find(color[x]);
}

void Union(int a, int b){
	if(a == b)	return;
	a = find(a);
	b = find(b);
	while(a != b){
		if(depth[b] > depth[a])
			swap(a, b);
		int x = find(parent[a]);
		color[a] = x;
		a = x;
	}
}

signed main(){
	fast_io();
	int n, k;
	cin >> n >> k;
	for(int i = 0; i < n-1; i++){
		int a, b;
		cin >> a >> b;
		graph[a].pb(b);
		graph[b].pb(a);
	}
	for(int i = 1; i <= n; i++){
		int indx;	cin >> indx;
		state[indx].pb(i);
	}
	dfs(1, -1, 0);
	for(int i = 1; i <= n; i++)	color[i] = i;
	for(int i = 1; i <= k; i++){
		for(int j = 1; j < state[i].size(); j++){
			Union(state[i][j], state[i][j-1]);
		}
	}
	for(int i = 1; i <= n; i++){
		for(auto x: graph[i]){
			if(find(i) == find(x))	continue;
			degree[find(i)].insert(find(x));
		}
	}
	int ans = 0;
	for(int i = 1; i <= k; i++){
		if(degree[i].size() == 1)	ans++;
	}
	cout << (ans+1)/2 << "\n";
	return 0;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:69:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j = 1; j < state[i].size(); j++){
                  ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 24
• Subtask 3: 0 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30