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| #include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;
const int oo = 0x3f3f3f3f;
const int MAX = 120;
const int head = 0;
int up[MAX * MAX], down[MAX * MAX], left[MAX * MAX], right[MAX * MAX];
int cnt[MAX], h[MAX], col[MAX * MAX];
int K, ans;
int nc;
void remove(const int& c) {
for (int i = down[c]; i != c; i = down[i]) {
left[right[i]] = left[i];
right[left[i]] = right[i];
cnt[col[i]]--;
}
}
void resume(const int& c) {
for (int i = up[c]; i != c; i = up[i]) {
left[right[i]] = i;
right[left[i]] = i;
cnt[col[i]]++;
}
}
int evalute() {
bool vis[MAX] = {0};
int ret = 0;
for (int i = right[head]; i != head; i = right[i]) {
if (!vis[i]) {
ret++;
vis[i] = true;
for (int j = down[i]; j != i; j = down[j]) {
for (int k = right[j]; k != j; k = right[k]) {
vis[col[k]] = true;
}
}
}
}
return ret;
}
bool dfs(const int& k) {
if (k + evalute() > ans) {
return false;
}
if (right[head] == head) {
return true;
}
int s = oo, c = 0;
for (int i = right[head]; i != head; i = right[i]) {
if (cnt[i] < s) {
s = cnt[i];
c = i;
if (cnt[i] <= 1) {
break;
}
}
}
for (int i = down[c]; i != c; i = down[i]) {
remove(i);
for (int j = right[i]; j != i; j = right[j]) {
remove(j);
}
if (dfs(k + 1)) {
return true;
}
for (int j = left[i]; j != i; j = left[j]) {
resume(j);
}
resume(i);
}
return false;
}
void init() {
for (int i = 0; i <= nc; i++) {
h[i] = -1;
left[i] = i - 1;
right[i] = i + 1;
up[i] = down[i] = i;
cnt[i] = 0;
col[i] = i;
}
left[head] = nc;
right[nc] = head;
K = nc;
for (int i = 1; i <= nc; i++) {
h[i] = -1;
}
}
void add(const int& r, const int& c) {
K++;
col[K] = c;
up[K] = c;
down[K] = down[c];
if (h[r] == -1) {
h[r] = right[K] = K;
}
left[K] = h[r];
right[K] = right[h[r]];
left[right[K]] = K;
right[left[K]] = K;
up[down[K]] = K;
down[up[K]] = K;
}
struct Node {
int x, y;
} city[MAX];
int dis[MAX][MAX];
int que[MAX * MAX], top;
int sqr(int x) { return x * x; }
int operator*(const Node& a, const Node& b) {
return sqr(a.x - b.x) + sqr(a.y - b.y);
}
void build(const int& mid) {
init();
for (int i = 1; i <= nc; i++) {
for (int j = 1; j <= nc; j++) {
if (dis[i][j] <= mid) {
add(i, j);
}
}
}
}
void run() {
int l = 0, r = top;
int mid, ans;
while (l <= r) {
mid = (l + r) / 2;
build(que[mid]);
if (dfs(0)) {
ans = que[mid];
r = mid - 1;
} else {
l = mid + 1;
}
}
printf("%.6f\n", sqrt((double)ans));
}
int main() {
int T;
scanf("%d", &T);
while (T--) {
scanf("%d%d", &nc, &ans);
for (int i = 1; i <= nc; i++) {
scanf("%d%d", &city[i].x, &city[i].y);
}
top = 0;
for (int i = 1; i <= nc; i++) {
for (int j = 1; j <= nc; j++) {
que[top++] = dis[i][j] = city[i] * city[j];
}
}
int tmp = top;
sort(que, que + top);
top = 1;
for (int i = 1; i < tmp; i++) {
if (que[i] != que[i - 1]) {
que[top++] = que[i];
}
}
run();
}
return 0;
}
|