Submission #988545

#	Time	Username	Problem	Language	Result	Execution time	Memory
988545		KasymK	Race (IOI11_race)	C++17	43 / 100	280 ms	120916 KiB

race

#include "bits/stdc++.h"
#define MAX_N 500000
#define ff first
#define ss second
using namespace std;
const int M = 2e5 + 5;
const int INF = 1e9;
vector<pair<int, int>> adj[M];
int vis[M], dis[M], edge[M], dp[M][105];
int answer = INF, Ka;
void dfs(int nd, int pr = -1){
	dp[nd][0] = 0;
	for(int i = 1; i <= Ka; ++i)
		dp[nd][i] = INF;
	for(auto &i : adj[nd])
		if(i.ff != pr){
			dfs(i.ff, nd);
//			jogaby tazele
			for(int a1 = 0; a1 + i.ss <= Ka; ++a1){
				int a2 = Ka - a1 - i.ss;
				answer = min(answer, dp[nd][a1] + dp[i.ff][a2] + 1);
			}
//			dp-ni tazele
			for(int k = 0; k + i.ss <= Ka; ++k)
				dp[nd][k+i.ss] = min(dp[nd][k+i.ss], dp[i.ff][k] + 1);
		}
}

int best_path(int n, int k, int H[][2], int L[]){
	Ka = k;
	for(int i = 0; i < n - 1; ++i)
		adj[H[i][0]].push_back({H[i][1], L[i]}), adj[H[i][1]].push_back({H[i][0], L[i]});
	if(n <= 1e3 + 5){
		queue<int> q;
		for(int ad = 0; ad < n; ++ad){
			for(int i = 0; i <= n; ++i)
				vis[i] = 0, dis[i] = 0, edge[i] = 0;
			while(!q.empty())
				q.pop();
			q.push(ad);
			vis[ad] = 1;
			while(!q.empty()){
				int x = q.front();
				q.pop();
				for(auto &i : adj[x])
					if(!vis[i.ff]){
						vis[i.ff] = 1;
						q.push(i.ff);
						dis[i.ff] = dis[x] + i.ss;
						edge[i.ff] = edge[x] + 1;
					}
			}
//			dis[i] = ad-den i-e cenli uzaklyk
//			tree-da dine bir path bar
			for(int i = 0; i < n; ++i)
				if(dis[i] == k)
					answer = min(answer, edge[i]);	
		}
	}
	else if(k <= 100)
		dfs(1);
	return (answer == INF ? -1 : answer);
	assert(false);
}

//int H[MAX_N][2], L[MAX_N], solution;
//
//int main(){
//	int n, k;
//	scanf("%d%d", &n, &k);
//	for(int i = 0; i < n - 1; ++i) scanf("%d%d%d", &H[i][0], &H[i][1], &L[i]);
//	scanf("%d", &solution);
//	int answer = best_path(n, k, H, L);
//	if(answer == solution)
//		puts("Correct.");
//	else
//		printf("Incorrect. Returned %d, Expected %d.", answer, solution);
//	return 0;
//}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 22 / 22
• Subtask 4: 0 / 57