Submission #805258

#	Time	Username	Problem	Language	Result	Execution time	Memory
805258		Halym2007	Race (IOI11_race)	C++11	21 / 100	3044 ms	10124 KiB

race

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
const int MAX_N = 200005;
vector <int> v[MAX_N];
int k, jog, par[MAX_N], cost[MAX_N];
map <int, int> m;

void dfs1 (int x, int pr) {
	par[x] = pr;
	for (int i : v[x]) {
		if (i != pr) {
			dfs1 (i, x);
		}
	}
}
void dfs2 (int x, int pr, int edges, int baha) {
	if (baha > k) return;
	m[baha] = edges;
	for (int i : v[x]) {
		if (i != pr and i != par[x]) {
			dfs2 (i, pr, edges + 1, baha + cost[i]);
		}
	}
}
void dfs (int x, int pr, int baha, int edges) {
	if (baha > k or pr == -1) {
		return;	
	}
	if ((baha + cost[x]) == k) {
		if (jog == -1) jog = edges + 1;
		else jog = min (jog, edges + 1);
		return;
	}
	m.clear();
	dfs2 (pr, x, 0, 0);
	int jp = baha + cost[x];
	if (m.find (k - jp) != m.end()) {
		if (jog == -1) jog = edges + m[k - jp] + 1;
		else jog = min (jog, edges + m[k - jp] + 1);
	}
	dfs (pr, par[pr], baha + cost[x], edges + 1);
}
int best_path(int N, int K, int H[][2], int L[]) {
	jog = -1;
	k = K;
	for (int i = 0; i < N - 1	; ++i) {
		v[H[i][0]].pb (H[i][1]);
		v[H[i][1]].pb (H[i][0]);
	}
	dfs1 (1, -1);
	for (int i = 0; i < N - 1; ++i) {
		if (par[H[i][0]] == H[i][1]) {
			cost[H[i][0]] = L[i];
		}
		else if (par[H[i][1]] == H[i][0]) {
			cost[H[i][1]] = L[i];
		}
	}
	for (int i = 0; i < N; ++i) {
		dfs (i, par[i], 0, 0);
	}
	return jog;
}
//int main () {
//	freopen ("kk.txt", "r", stdin);
//	int N, K;
//	cin >> N >> K;
//	int H[N][2], L[N];
//	for (int i = 0; i < N; ++i) {
//		cin >> H[i][0] >> H[i][1] >> L[i];
//	}
////	best_path(N, K, H, L);
//	cout << best_path(N, K, H, L);
//}

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