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Submission #467235

# Submission time Handle Problem Language Result Execution time Memory
467235 2021-08-22T06:53:46 Z Leonardo_Paes Highway Tolls (IOI18_highway) C++17
100 / 100
 291 ms 11016 KB 
#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define f first
#define s second
 
/* ask with a vector saying the edge value (a or b) for each edge to know the smallest dist
    1) find an edge in the path S -> T:
         D&C in the edges, trying to find anyone that is in the path.
         To do so, just paint everything with A and get the min dist from S to T
         Then, in the D&C paint all edges at the current set with B, if it changes
         the distance from S to T, than of these edges is in the path.
    2) Let e be an edge in the path S -> T, how to find one of the endpoints, S or T ?
    	 multisource bfs from the endpoints of e. Then enumerate the edges 
    	 according to their distante. Do bb in the prefix of edges, the last one that
    	 changes the dist from S to T has S or T as the farthest endpoint. 
   	3) Just do step 2) again 
*/
const int maxn = 9e4 + 10;
vector<int> grafo[maxn];
 
int find_edge(int &n, int &m, vector<int> &u, vector<int> &v, int &a, int &b, ll &d){ // log m queries
	int l = 0, mid, r = m-1;
	while(l != r){
		mid = (l + r) >> 1;
		vector<int> aux(m, 0);
		for(int i=0; i<=mid; i++) aux[i] = 1;
		if(ask(aux) != d) r = mid;
		else l = mid + 1;
	}
	return l;
}
 
vector<int> bfs(int &n, int &m, int &a, int &b, ll &d, int root){
	queue<pii> fila;
	fila.push({root, 0});
	vector<int> dist(n, -1);
	while(!fila.empty()){
		int x = fila.front().f, dis = fila.front().s;
		fila.pop();
		if(dist[x] != -1) continue;
		dist[x] = dis;
		for(int viz : grafo[x]) fila.push({viz, dis+1});
	}
	return dist;
}
 
pii find_endpoints(int &n, int &m, vector<int> &u, vector<int> &v, int &a, int &b, ll &d, int &e){ // 2*log m queries
	vector<int> dist[2];
	dist[0] = bfs(n, m, a, b, d, u[e]);
	dist[1] = bfs(n, m, a, b, d, v[e]);
	pii ans = {0, 0};
	vector<pii> sbt[2];
	for(int i=0; i<n; i++){
		if(dist[0][i] <= dist[1][i]) sbt[0].push_back({dist[0][i], i});
		else sbt[1].push_back({dist[1][i], i});
	}
	for(int i=0; i<2; i++) sort(sbt[i].begin(), sbt[i].end());
	for(int j=0; j<2; j++){
		int ini = 0, meio, fim = (int)sbt[j].size() - 1;
		while(ini != fim){
			meio = (ini + fim + 1) >> 1;
			vector<int> aux(m, 0);
			vector<bool> mark(n, 0);
			for(int i=meio; i<sbt[j].size(); i++) mark[sbt[j][i].s] = 1;
			for(int i=0; i<m; i++) if(mark[u[i]] != mark[v[i]]) aux[i] = 1;
			if(ask(aux) != d) ini = meio;
			else fim = meio - 1;
		}
		if(j) ans.f = sbt[j][ini].s;
		else ans.s = sbt[j][ini].s;
	}
	return ans;
 }
 
void find_pair(int n, vector<int> u, vector<int> v, int a, int b) {  
	int m = u.size();
	for(int i=0; i<m; i++){
		grafo[u[i]].push_back(v[i]);
		grafo[v[i]].push_back(u[i]);
	}
	vector<int> aux(m, 0); // 1 query
	ll d = ask(aux);
	int e = find_edge(n, m, u, v, a, b, d);
	pii ans = find_endpoints(n, m, u, v, a, b, d, e);
	answer(ans.f, ans.s);
	/*
4 4
1
3
1
3
0 1 
0 2
0 3
1 2
	*/
}

Compilation message

highway.cpp: In function 'pii find_endpoints(int&, int&, std::vector<int>&, std::vector<int>&, int&, int&, ll&, int&)':
highway.cpp:67:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   67 |    for(int i=meio; i<sbt[j].size(); i++) mark[sbt[j][i].s] = 1;
      |                    ~^~~~~~~~~~~~~~

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2376 KB Output is correct
2 Correct 2 ms 2376 KB Output is correct
3 Correct 2 ms 2412 KB Output is correct
4 Correct 2 ms 2376 KB Output is correct
5 Correct 2 ms 2376 KB Output is correct
6 Correct 2 ms 2376 KB Output is correct
7 Correct 2 ms 2376 KB Output is correct
8 Correct 3 ms 2376 KB Output is correct
9 Correct 2 ms 2412 KB Output is correct
10 Correct 2 ms 2376 KB Output is correct
11 Correct 2 ms 2376 KB Output is correct
12 Correct 2 ms 2376 KB Output is correct

Subtask #2
7.0 / 7.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 2376 KB Output is correct
2 Correct 16 ms 3144 KB Output is correct
3 Correct 147 ms 9376 KB Output is correct
4 Correct 164 ms 9408 KB Output is correct
5 Correct 145 ms 9356 KB Output is correct
6 Correct 184 ms 9452 KB Output is correct
7 Correct 171 ms 9428 KB Output is correct
8 Correct 147 ms 9348 KB Output is correct
9 Correct 188 ms 9392 KB Output is correct
10 Correct 194 ms 9432 KB Output is correct
11 Correct 187 ms 8976 KB Output is correct
12 Correct 224 ms 9172 KB Output is correct
13 Correct 137 ms 9168 KB Output is correct
14 Correct 193 ms 9168 KB Output is correct

Subtask #3
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 3144 KB Output is correct
2 Correct 37 ms 3812 KB Output is correct
3 Correct 53 ms 4480 KB Output is correct
4 Correct 165 ms 8956 KB Output is correct
5 Correct 161 ms 8952 KB Output is correct
6 Correct 157 ms 9276 KB Output is correct
7 Correct 124 ms 9224 KB Output is correct
8 Correct 111 ms 8932 KB Output is correct
9 Correct 164 ms 9200 KB Output is correct

Subtask #4
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 2376 KB Output is correct
2 Correct 17 ms 3264 KB Output is correct
3 Correct 156 ms 7932 KB Output is correct
4 Correct 169 ms 9256 KB Output is correct
5 Correct 186 ms 9324 KB Output is correct
6 Correct 178 ms 9300 KB Output is correct
7 Correct 182 ms 9424 KB Output is correct
8 Correct 136 ms 9448 KB Output is correct
9 Correct 216 ms 9416 KB Output is correct
10 Correct 143 ms 9324 KB Output is correct
11 Correct 146 ms 9128 KB Output is correct
12 Correct 181 ms 9172 KB Output is correct
13 Correct 186 ms 9196 KB Output is correct
14 Correct 149 ms 8784 KB Output is correct
15 Correct 190 ms 9396 KB Output is correct
16 Correct 141 ms 9436 KB Output is correct
17 Correct 141 ms 9172 KB Output is correct
18 Correct 135 ms 9184 KB Output is correct
19 Correct 190 ms 9500 KB Output is correct
20 Correct 190 ms 9188 KB Output is correct
21 Correct 179 ms 9832 KB Output is correct
22 Correct 175 ms 9904 KB Output is correct
23 Correct 184 ms 9572 KB Output is correct
24 Correct 141 ms 9536 KB Output is correct
25 Correct 139 ms 9200 KB Output is correct

Subtask #5
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 3232 KB Output is correct
2 Correct 24 ms 3216 KB Output is correct
3 Correct 169 ms 9620 KB Output is correct
4 Correct 176 ms 9908 KB Output is correct
5 Correct 282 ms 10604 KB Output is correct
6 Correct 243 ms 10668 KB Output is correct
7 Correct 283 ms 10780 KB Output is correct
8 Correct 203 ms 10608 KB Output is correct
9 Correct 165 ms 8504 KB Output is correct
10 Correct 167 ms 9048 KB Output is correct
11 Correct 222 ms 8844 KB Output is correct
12 Correct 218 ms 9892 KB Output is correct
13 Correct 222 ms 10408 KB Output is correct
14 Correct 288 ms 10436 KB Output is correct
15 Correct 270 ms 10284 KB Output is correct
16 Correct 252 ms 8908 KB Output is correct
17 Correct 150 ms 9844 KB Output is correct
18 Correct 158 ms 9892 KB Output is correct
19 Correct 144 ms 9820 KB Output is correct
20 Correct 150 ms 10052 KB Output is correct
21 Correct 220 ms 10172 KB Output is correct

Subtask #6
31.0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 3144 KB Output is correct
2 Correct 23 ms 3264 KB Output is correct
3 Correct 218 ms 9640 KB Output is correct
4 Correct 200 ms 9840 KB Output is correct
5 Correct 241 ms 9948 KB Output is correct
6 Correct 281 ms 11016 KB Output is correct
7 Correct 158 ms 9776 KB Output is correct
8 Correct 170 ms 9768 KB Output is correct
9 Correct 246 ms 9852 KB Output is correct
10 Correct 278 ms 10728 KB Output is correct
11 Correct 269 ms 10648 KB Output is correct
12 Correct 275 ms 10560 KB Output is correct
13 Correct 231 ms 8876 KB Output is correct
14 Correct 171 ms 9012 KB Output is correct
15 Correct 214 ms 9048 KB Output is correct
16 Correct 158 ms 9028 KB Output is correct
17 Correct 191 ms 9080 KB Output is correct
18 Correct 232 ms 9056 KB Output is correct
19 Correct 212 ms 10368 KB Output is correct
20 Correct 263 ms 10308 KB Output is correct
21 Correct 291 ms 10696 KB Output is correct
22 Correct 266 ms 10512 KB Output is correct
23 Correct 280 ms 10640 KB Output is correct
24 Correct 217 ms 10484 KB Output is correct
25 Correct 224 ms 10428 KB Output is correct
26 Correct 254 ms 10420 KB Output is correct
27 Correct 178 ms 10064 KB Output is correct
28 Correct 185 ms 9864 KB Output is correct
29 Correct 190 ms 10172 KB Output is correct
30 Correct 177 ms 10056 KB Output is correct
31 Correct 189 ms 9932 KB Output is correct
32 Correct 148 ms 9844 KB Output is correct
33 Correct 152 ms 9980 KB Output is correct
34 Correct 161 ms 9880 KB Output is correct
35 Correct 194 ms 9972 KB Output is correct
36 Correct 158 ms 9808 KB Output is correct
37 Correct 156 ms 10192 KB Output is correct
38 Correct 144 ms 10064 KB Output is correct
39 Correct 195 ms 10376 KB Output is correct
40 Correct 258 ms 10152 KB Output is correct
41 Correct 260 ms 10152 KB Output is correct
42 Correct 254 ms 9916 KB Output is correct