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답안 #445204

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
445204 2021-07-16T20:26:03 Z Tizariox 경주 (Race) (IOI11_race) C++14
21 / 100
 3000 ms 25556 KB 
#include "race.h"
#include <bits/stdc++.h>
using namespace std;
 
using ll = long long;
using pii = pair<int, int>;
 
#define MOD 1000000007
#define nl "\n"
#define pb push_back
 
int n, k;
vector<pii> adjLists[200000];
int par[200000];
int subTreeSize[200000];
bool vis[200000];
 
int dist[200000];
int anc[200000][19];
 
void findAncestors() {
	for (int i = 0; i < n; i++) {
		if (dist[i] != 0) {
			anc[i][0] = par[i];
		}
	}
	for (int j = 1; j <= 18; j++) {
		for (int i = 0; i < n; i++) {
			if (dist[i] != 0) {
				anc[i][j] = anc[anc[i][j - 1]][j - 1];
			}
		}
	}
}
 
void treeDfs2(int node, int prevNode) {
	for (int i = 0; i < adjLists[node].size(); i++) {
		if (adjLists[node][i].first != prevNode) {
			pii child = adjLists[node][i];
			par[child.first] = node;
			dist[child.first] = dist[node] + 1;
			treeDfs2(child.first, node);
		}
	}
}
 
int lca(int a, int b) {
	if (dist[a] > dist[b]) { // swap if a is further
		return lca(b, a);
	}
	if (dist[a] < dist[b]) { // find ancestor of b that's the same depth as a
		for (int k = 18; dist[b] != dist[a]; k--) {
			while (dist[b] - (1 << k) >= dist[a]) {
				b = anc[b][k];
			}
		}
	}
	for (int k = 18; k > 0; k--) {
		while (anc[a][k] != anc[b][k]) {
			a = anc[a][k];
			b = anc[b][k];
		}
	}
	while (a != b) {
		a = par[a];
		b = par[b];
	}
	return a;
}
 
int distance(int a, int b) {
	int ancestor = lca(a, b);
	return dist[a] + dist[b] - 2 * dist[ancestor];
}
 
void calcSubtrees(int node) {
	for (pii i : adjLists[node]) {
		if (i.first != par[node]) {
			calcSubtrees(i.first);
			subTreeSize[node] += subTreeSize[i.first];
		}
	}
}
 
unordered_set<int> visited;
 
int findCentroid(int node) {
	// we don't need to worry about the parent and its subtrees because we
	// already know it's not a centroid
	visited.insert(node);
	for (pii i : adjLists[node]) {
		if (visited.count(i.first) == 0) {
			if (subTreeSize[i.first] * 2 > n) {
				return findCentroid(i.first);
			} else {
				return node;
			}
		}
	}
	return -1;
}
 
int minOverallPath = 1e9;
int minPath;
 
void treeDfs1(int node, int path, int root) {
	if (path == k) {
		minPath = min(minPath, distance(node, root));
		return;
	}
	visited.insert(node);
	for (int i = 0; i < adjLists[node].size(); i++) {
		pii child = adjLists[node][i];
		if (visited.count(child.first) > 0 || vis[child.first]) {
			continue;
		}
		treeDfs1(child.first, path + child.second, root);
	}
}
 
unordered_map<int, pii> nodeDists;
queue<pair<int, pii>> nodeDistsQueue;
 
void treeDfs3(int node, int path, int root) {
	if (nodeDists.find(path) != nodeDists.end()) {
		if (distance(node, root) < (*nodeDists.find(path)).second.second) {
			nodeDists[path] = pii(distance(node, root), node);
		} 
	} else {
		nodeDistsQueue.push(make_pair(path, pii(distance(node, root), node)));
		if (nodeDists.find(k - path) != nodeDists.end()) {
			minPath = min(minPath, distance(node, root) + distance((*nodeDists.find(k - path)).second.second, root));
		}
	}
	visited.insert(node);
	for (int i = 0; i < adjLists[node].size(); i++) {
		pii child = adjLists[node][i];
		if (visited.count(child.first) > 0 || vis[child.first]) {
			continue;
		}
		treeDfs3(child.first, path + child.second, root);
	}
}
 
void decomp(int node) {
	int centroid = findCentroid(node);
	vis[centroid] = true;
	minPath = 1e9;
	treeDfs1(centroid, 0, centroid);
	visited.clear();
	for (pii i : adjLists[centroid]) {
		if (vis[i.first]) {
			continue;
		}
		treeDfs3(i.first, i.second, centroid);
		visited.clear();
		while (!nodeDistsQueue.empty()) {
			nodeDists.insert(nodeDistsQueue.front());
			nodeDistsQueue.pop();
		}
	}
	nodeDists.clear();
	minOverallPath = min(minOverallPath, minPath);
	for (pii i : adjLists[centroid]) {
		if (!vis[i.first]) {
			decomp(i.first);
		}
	}
}

int best_path(int n1, int k1, int inputs[][2], int l[]) {
  n = n1;
  k = k1;
  for (int i = 0; i < n - 1; i++) {
  	adjLists[inputs[i][0]].pb(pii(inputs[i][1], l[i]));
	adjLists[inputs[i][1]].pb(pii(inputs[i][0], l[i]));
  }
  	treeDfs2(0, -1);
	findAncestors();
	calcSubtrees(0);
	decomp(0);
	return ((minOverallPath == 1e9) ? -1 : minOverallPath);
}
 
#ifdef LOCAL
int inputs[200000][2];
int l[200000];
int main() {
  	freopen("grader.in.5", "r", stdin);
    freopen("out.txt", "w", stdout);
  int n1, k1;
	cin >> n1 >> k1;
	for (int i = 0; i < n1 - 1; i++) {
      	cin >> inputs[i][0] >> inputs[i][1] >> l[i];
	}
  cout << best_path(n1, k1, inputs, l) << "\n";
}
#endif

Compilation message

race.cpp: In function 'void treeDfs2(int, int)':
race.cpp:37:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |  for (int i = 0; i < adjLists[node].size(); i++) {
      |                  ~~^~~~~~~~~~~~~~~~~~~~~~~
race.cpp: In function 'void treeDfs1(int, int, int)':
race.cpp:112:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  112 |  for (int i = 0; i < adjLists[node].size(); i++) {
      |                  ~~^~~~~~~~~~~~~~~~~~~~~~~
race.cpp: In function 'void treeDfs3(int, int, int)':
race.cpp:136:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  136 |  for (int i = 0; i < adjLists[node].size(); i++) {
      |                  ~~^~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
9.0 / 9.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 4940 KB Output is correct
2 Correct 4 ms 5068 KB Output is correct
3 Correct 5 ms 5068 KB Output is correct
4 Correct 4 ms 5068 KB Output is correct
5 Correct 4 ms 5004 KB Output is correct
6 Correct 4 ms 4940 KB Output is correct
7 Correct 5 ms 5012 KB Output is correct
8 Correct 5 ms 5004 KB Output is correct
9 Correct 5 ms 5068 KB Output is correct
10 Correct 5 ms 5068 KB Output is correct
11 Correct 5 ms 4940 KB Output is correct
12 Correct 5 ms 5068 KB Output is correct
13 Correct 4 ms 5068 KB Output is correct
14 Correct 4 ms 4940 KB Output is correct
15 Correct 5 ms 5068 KB Output is correct
16 Correct 5 ms 5068 KB Output is correct
17 Correct 4 ms 4940 KB Output is correct
18 Correct 4 ms 5068 KB Output is correct

Subtask #2
12.0 / 12.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 4940 KB Output is correct
2 Correct 4 ms 5068 KB Output is correct
3 Correct 5 ms 5068 KB Output is correct
4 Correct 4 ms 5068 KB Output is correct
5 Correct 4 ms 5004 KB Output is correct
6 Correct 4 ms 4940 KB Output is correct
7 Correct 5 ms 5012 KB Output is correct
8 Correct 5 ms 5004 KB Output is correct
9 Correct 5 ms 5068 KB Output is correct
10 Correct 5 ms 5068 KB Output is correct
11 Correct 5 ms 4940 KB Output is correct
12 Correct 5 ms 5068 KB Output is correct
13 Correct 4 ms 5068 KB Output is correct
14 Correct 4 ms 4940 KB Output is correct
15 Correct 5 ms 5068 KB Output is correct
16 Correct 5 ms 5068 KB Output is correct
17 Correct 4 ms 4940 KB Output is correct
18 Correct 4 ms 5068 KB Output is correct
19 Correct 3 ms 5004 KB Output is correct
20 Correct 3 ms 4940 KB Output is correct
21 Correct 8 ms 5196 KB Output is correct
22 Correct 11 ms 5248 KB Output is correct
23 Correct 15 ms 5244 KB Output is correct
24 Correct 9 ms 5240 KB Output is correct
25 Correct 8 ms 5196 KB Output is correct
26 Correct 8 ms 5148 KB Output is correct
27 Correct 7 ms 5196 KB Output is correct
28 Correct 9 ms 5196 KB Output is correct
29 Correct 8 ms 5144 KB Output is correct
30 Correct 8 ms 5144 KB Output is correct
31 Correct 8 ms 5196 KB Output is correct
32 Correct 8 ms 5196 KB Output is correct
33 Correct 10 ms 5248 KB Output is correct
34 Correct 46 ms 5196 KB Output is correct
35 Correct 58 ms 5196 KB Output is correct
36 Correct 66 ms 5196 KB Output is correct
37 Correct 36 ms 5196 KB Output is correct
38 Correct 25 ms 5232 KB Output is correct

Subtask #3
0 / 22.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 4940 KB Output is correct
2 Correct 4 ms 5068 KB Output is correct
3 Correct 5 ms 5068 KB Output is correct
4 Correct 4 ms 5068 KB Output is correct
5 Correct 4 ms 5004 KB Output is correct
6 Correct 4 ms 4940 KB Output is correct
7 Correct 5 ms 5012 KB Output is correct
8 Correct 5 ms 5004 KB Output is correct
9 Correct 5 ms 5068 KB Output is correct
10 Correct 5 ms 5068 KB Output is correct
11 Correct 5 ms 4940 KB Output is correct
12 Correct 5 ms 5068 KB Output is correct
13 Correct 4 ms 5068 KB Output is correct
14 Correct 4 ms 4940 KB Output is correct
15 Correct 5 ms 5068 KB Output is correct
16 Correct 5 ms 5068 KB Output is correct
17 Correct 4 ms 4940 KB Output is correct
18 Correct 4 ms 5068 KB Output is correct
19 Execution timed out 3061 ms 25556 KB Time limit exceeded
20 Halted 0 ms 0 KB -

Subtask #4
0 / 57.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 4940 KB Output is correct
2 Correct 4 ms 5068 KB Output is correct
3 Correct 5 ms 5068 KB Output is correct
4 Correct 4 ms 5068 KB Output is correct
5 Correct 4 ms 5004 KB Output is correct
6 Correct 4 ms 4940 KB Output is correct
7 Correct 5 ms 5012 KB Output is correct
8 Correct 5 ms 5004 KB Output is correct
9 Correct 5 ms 5068 KB Output is correct
10 Correct 5 ms 5068 KB Output is correct
11 Correct 5 ms 4940 KB Output is correct
12 Correct 5 ms 5068 KB Output is correct
13 Correct 4 ms 5068 KB Output is correct
14 Correct 4 ms 4940 KB Output is correct
15 Correct 5 ms 5068 KB Output is correct
16 Correct 5 ms 5068 KB Output is correct
17 Correct 4 ms 4940 KB Output is correct
18 Correct 4 ms 5068 KB Output is correct
19 Correct 3 ms 5004 KB Output is correct
20 Correct 3 ms 4940 KB Output is correct
21 Correct 8 ms 5196 KB Output is correct
22 Correct 11 ms 5248 KB Output is correct
23 Correct 15 ms 5244 KB Output is correct
24 Correct 9 ms 5240 KB Output is correct
25 Correct 8 ms 5196 KB Output is correct
26 Correct 8 ms 5148 KB Output is correct
27 Correct 7 ms 5196 KB Output is correct
28 Correct 9 ms 5196 KB Output is correct
29 Correct 8 ms 5144 KB Output is correct
30 Correct 8 ms 5144 KB Output is correct
31 Correct 8 ms 5196 KB Output is correct
32 Correct 8 ms 5196 KB Output is correct
33 Correct 10 ms 5248 KB Output is correct
34 Correct 46 ms 5196 KB Output is correct
35 Correct 58 ms 5196 KB Output is correct
36 Correct 66 ms 5196 KB Output is correct
37 Correct 36 ms 5196 KB Output is correct
38 Correct 25 ms 5232 KB Output is correct
39 Execution timed out 3061 ms 25556 KB Time limit exceeded
40 Halted 0 ms 0 KB -