Submission #562776

#	Time	Username	Problem	Language	Result	Execution time	Memory
562776		Bill_00	Capital City (JOI20_capital_city)	C++14	0 / 100	138 ms	49496 KiB

capital_city

#include <bits/stdc++.h>
#define N 1000000
using namespace std;
int range[N], n, k, city[N], ans[N], bef[N], pos, x[N];
vector<int> adj[N];
void dfs(int node, int par = 0){
	pos++;
//	cout << endl;
//	cout << pos << '\n';
	x[pos] = city[node];
	if(bef[city[node]] == 0){
		range[pos] = pos;
		bef[city[node]] = pos;
		ans[city[node]] = 1;
	}
	else{
		range[pos] = 1e9;
		int val = pos - 1;
		while(val > bef[city[node]]){
//			cout << val << ' ';
			if(range[val] > bef[city[node]]) ans[city[node]] += ans[x[val]];
			else ans[city[node]] += (ans[x[val]] - 1);
			range[pos] = min(range[pos], range[val]);
			val = range[val] - 1;
		}
//		cout << val << '\n';
		range[pos] = min(range[pos], range[bef[city[node]]]);
	}
//	cout << ans[city[node]] << '\n';
	for(int neigh : adj[node]){
		if(neigh != par) dfs(neigh, node);
	}
}
int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	cin >> n >> k;
	for(int i = 1; i < n; i++){
		int a, b;
		cin >> a >> b;
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	int leaf;
	for(int i = 1; i <= n; i++){
		cin >> city[i];
		if(adj[i].size() == 1) leaf = i;
	}
	dfs(leaf);
	int answer = 1e9;
	for(int i = 1; i <= k; i++){
//		cout << ans[i] << ' ';
		answer = min(answer, ans[i] - 1);
	}
//	cout << '\n';
	cout << answer;
}

Compilation message (stderr)

capital_city.cpp: In function 'int main()':
capital_city.cpp:51:5: warning: 'leaf' may be used uninitialized in this function [-Wmaybe-uninitialized]
   51 |  dfs(leaf);
      |  ~~~^~~~~~

• Subtask 1: 0 / 1
• Subtask 2: 0 / 10
• Subtask 3: 0 / 30
• Subtask 4: 0 / 59