이 제출은 이전 버전의 oj.uz에서 채점하였습니다. 현재는 제출 당시와는 다른 서버에서 채점을 하기 때문에, 다시 제출하면 결과가 달라질 수도 있습니다.
#include "towns.h"
#include <vector>
#include <map>
using namespace std;
class DSU {
private:
vector<int> par;
map<int, int> poz;
public:
DSU(const vector<int>& v) {
for (int i = 0; i < v.size(); ++i)
poz[v[i]] = i;
for (int i = 0; i < v.size(); ++i)
par.push_back(i);
}
int getRoot(int x) {
if (x == par[x])
return x;
return par[x] = getRoot(par[x]);
}
bool query(int a, int b) {
a = poz[a], b = poz[b];
int ra = getRoot(a);
int rb = getRoot(b);
return ra == rb;
}
void join(int a, int b) {
a = poz[a], b = poz[b];
int ra = getRoot(a);
int rb = getRoot(b);
par[ra] = rb;
}
};
int hubDistance(int N, int sub) {
vector<vector<int>> dist(N, vector<int>(N, -1));
auto getDist = [&dist](int a, int b) {
if (dist[a][b] == -1)
dist[a][b] = dist[b][a] = getDistance(a, b);
return dist[a][b];
};
int D1, D2, dist_max = 0;
for (int i = 1; i < N; ++i)
if (getDist(0, i) > dist_max) {
dist_max = getDist(0, i);
D1 = i;
}
dist_max = 0;
for (int i = 0; i < N; ++i)
if (i != D1 && getDist(D1, i) > dist_max) {
dist_max = getDist(D1, i);
D2 = i;
}
int R = getDist(D1, D2);
for (int i = 0; i < N; ++i)
if (i != D1 && i != 0) {
int dist_i = (getDist(i, D1) - getDist(i, 0) + getDist(D1, 0)) / 2;
R = min(R, max(dist_i, getDist(D1, D2) - dist_i));
}
vector<int> leaves1, leaves2;
int cnt1 = 0, cnt2 = 0;
int st = 0, dr = 0;
for (int i = 0; i < N; ++i) {
int dist_i = (getDist(i, D1) - getDist(i, 0) + getDist(D1, 0)) / 2;
if (R == max(dist_i, getDist(D1, D2) - dist_i)) {
if (R == dist_i) {
++cnt1;
leaves1.push_back(i);
} else {
++cnt2;
leaves2.push_back(i);
}
} else if (dist_i < getDist(D1, D2) - dist_i) {
++st;
} else {
++dr;
}
}
if (st > N / 2 || dr > N / 2)
return -R;
vector<int> leaves;
if (leaves1.size() > leaves2.size()) {
leaves = leaves1;
} else {
leaves = leaves2;
R = getDist(D1, D2) - R;
}
auto sameSubtree = [&dist, &D1, &D2, &getDist, &R](int a, int b) {
int dist_lca = (getDist(a, D1) + getDist(b, D1) - getDist(a, b)) / 2;
if (dist_lca <= R)
return false;
return true;
};
DSU dsu(leaves);
vector<int> cand = leaves;
int fin = leaves.back();
while (!cand.empty()) {
vector<int> new_cand;
for (int i = 0; i < cand.size(); i += 2) {
if (i < cand.size() - 1) {
if (sameSubtree(cand[i], cand[i + 1])) {
dsu.join(cand[i], cand[i + 1]);
new_cand.push_back(cand[i]);
}
} else {
fin = cand[i];
}
}
cand = new_cand;
}
int ap = 0;
for (auto i: leaves)
if (dsu.query(fin, i) || sameSubtree(fin, i))
++ap;
if (ap > N / 2)
return -R;
return R;
}
컴파일 시 표준 에러 (stderr) 메시지
towns.cpp: In constructor 'DSU::DSU(const std::vector<int>&)':
towns.cpp:13:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
13 | for (int i = 0; i < v.size(); ++i)
| ~~^~~~~~~~~~
towns.cpp:15:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
15 | for (int i = 0; i < v.size(); ++i)
| ~~^~~~~~~~~~
towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:101:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
101 | for (int i = 0; i < cand.size(); i += 2) {
| ~~^~~~~~~~~~~~~
towns.cpp:102:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
102 | if (i < cand.size() - 1) {
| ~~^~~~~~~~~~~~~~~~~
towns.cpp:37:28: warning: unused parameter 'sub' [-Wunused-parameter]
37 | int hubDistance(int N, int sub) {
| ~~~~^~~
towns.cpp:40:15: warning: 'D1' may be used uninitialized in this function [-Wmaybe-uninitialized]
40 | if (dist[a][b] == -1)
| ^
towns.cpp:41:44: warning: 'D2' may be used uninitialized in this function [-Wmaybe-uninitialized]
41 | dist[a][b] = dist[b][a] = getDistance(a, b);
| ~~~~~~~~~~~^~~~~~
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