Submission #1000748

#	Time	Username	Problem	Language	Result	Execution time	Memory
1000748		Nomio	Race (IOI11_race)	C++17	9 / 100	38 ms	15832 KiB

race

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
vector<int> adj[1001];
ll dis[1001][1001] {};
int d[1001][1001], D[1001][1001];
void bfs(int x) {
	queue<int> q;
	dis[x][x] = 0;
	D[x][x] = 0;
	q.push(x);
	while(!q.empty()) {
		int X = q.front();
		q.pop();
		for(int y : adj[X]) {
			if(dis[x][y] == -1) {
				q.push(y);
				dis[x][y] = dis[x][X] + d[X][y];
				D[x][y] = D[x][X] + 1;
			}
		}
	}
}
int best_path(int n, int k, int H[][2], int L[]) {
	for(int i = 0; i <= n; i++) {
		adj[i].clear();
	}
	for(int i = 0; i <= n; i++) {
		for(int j = 0; j <= n; j++) {
			D[i][j] = 0;
			d[i][j] = -1;
			if(i == j) {
				d[i][j] = 0;
			}
		}
	}
	for(int i = 0; i < n - 1; i++) {
		int a, b;
		a = H[i][0];
		b = H[i][1];
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	for(int i = 0; i < n - 1; i++) {
		d[H[i][0]][H[i][1]] = L[i];
		d[H[i][1]][H[i][0]] = L[i];
	}
	if(n <= 100 && k <= 100) {
		int S[n + 1] {};
		for(int i = 0; i < n - 1; i++) {
			S[i + 2] = S[i + 1] + L[i];
		}
		int mn = n;
		for(int i = 2; i <= n; i++) {
			for(int j = 1; j <= i - 1; j++) {
				if(S[i] - S[j] == k) {
					mn = min(mn, i - j);
				}
			}
		}
		if(mn == n) mn = -1; 
		return mn;
	} else {
		for(int i = 0; i < n; i++) {
			for(int j = 0; j < n; j++) {
				if(i == j) continue;
				bfs(i);
			}
		}
		int mn = 1e9;
		for(int i = 0; i < n; i++) {
			for(int j = 0; j < n; j++) {
				if(i == j) continue;
				if(dis[i][j] == k) {
					mn = min(mn, D[i][j]);
				}
			}
		}
		if(mn == 1e9) mn = -1;
		return mn;
	}
}
//int main() {
//	cout << best_path(3, 3, {{0, 1}, {1, 2}}, {1, 1}) << '\n';
//	return 0;
//}

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