Submission #1101832

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
1101832	2024-10-17T01:27:55 Z	shidou26	Race (IOI11_race)	C++14	Compilation error	0 ms	0 KB

race

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

#define endl '\n'
#define all(v) v.begin(), v.end()

typedef long long ll;
typedef pair<int, int> ii;

const int N = 1e6 + 3;
const int INF = 1e9 + 3;

int n, k;
vector<ii> adj[N];

int deepest = 0, answer = INF;
int siz[N], dp[N];
bool is_centroid[N];

void input() {
	cin >> n >> k;

	for(int i = 1; i < n; i++) {
		int u, v, d; cin >> u >> v >> d;
		u++; v++;
		// cout << u << " " << v << endl;
		adj[u].push_back({v, d});
		adj[v].push_back({u, d});
	}	
}

void dfs(int u, int previous) {
	siz[u] = 1;
	for(ii p : adj[u]) {
		int v = p.first;
		if(v != previous && !is_centroid[v]) {
			dfs(v, u);
			siz[u] += siz[v];
		}
	}
}

int find_centroid(int u, int tree_size, int previous) {
	for(ii p : adj[u]) {
		int v = p.first;
		if(v != previous && !is_centroid[v] && siz[v] * 2 > tree_size) {
			return find_centroid(v, tree_size, u);
		}
	}	
	return u;
}

void get(int u, int previous, int height, int edge) {
	if(height <= k) answer = min(answer, edge + dp[k - height]);
	// cout << u << " " << edge << " " << height << endl;
	for(ii p : adj[u]) {
		int v, d; tie(v, d) = p;
		if(v != previous && !is_centroid[v]) {
			get(v, u, height + d, edge + 1);
		}
	}
}

void update(int u, int previous, int height, int edge) {
	if(height <= k) dp[height] = min(dp[height], edge), deepest = max(deepest, height);
	for(ii p : adj[u]) {
		int v, d; tie(v, d) = p;
		if(v != previous && !is_centroid[v]) {
			update(v, u, height + d, edge + 1);
		}
	}
}

void build_centroid(int u) {
	dfs(u, -1);
	int centroid = find_centroid(u, siz[u], -1);

	deepest = 0; dp[0] = 0; 
	for(ii p : adj[centroid]) {
		int v, d; tie(v, d) = p;
		if(!is_centroid[v]) {
			get(v, centroid, d, 1);
			update(v, centroid, d, 1);
			// cout << endl;
		}
	}
	for(int i = 0; i <= deepest; i++) dp[i] = INF;

	is_centroid[centroid] = true;
	for(ii p : adj[centroid]) {
		int v = p.first;
		if(!is_centroid[v]) {
	//		cout << v << endl;
			build_centroid(v);
		}
	}
}

void process() {
	for(int i = 0; i <= k; i++) dp[i] = INF;
	build_centroid(1);
	cout << (answer == INF ? -1 : answer) << endl;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	#define task "DateALive"
	if(fopen(task".INP", "r")) {
		freopen(task".INP", "r", stdin);
		freopen(task".OUT", "w", stdout);
	}

	input();
	process();

	return 0;
}

Compilation message

race.cpp: In function 'int main()':
race.cpp:111:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |   freopen(task".INP", "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
race.cpp:112:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |   freopen(task".OUT", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/cc7FFzIP.o: in function `main':
race.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/cccfUj6R.o:grader.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/cccfUj6R.o: in function `main':
grader.cpp:(.text.startup+0x28): undefined reference to `best_path(int, int, int (*) [2], int*)'
collect2: error: ld returned 1 exit status