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#include <bits/stdc++.h>
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#pragma GCC optimize("Ofast")
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#define endl "\n"
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#define ll long long
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#define mod 1000000007
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#define MAX 1000000
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#define PI 3.14159265
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using namespace std;
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ll n, c;
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ll arr[MAX];
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bool canbe(ll m) {
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int cow_placed = 1, last_pos = arr[0];
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for (ll i = 0; i < n; i++) {
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if ((arr[i] - last_pos) >= m) {
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if (++cow_placed == c) {
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return true;
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}
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last_pos = arr[i];
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}
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}
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return false;
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}
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int main()
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{
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ios_base::sync_with_stdio(0);
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cin.tie(0); cout.tie(0);
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ll times; cin >> times; while (times--) {
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cin >> n >> c;
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for (ll i = 0; i < n; i++) {
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cin >> arr[i];
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}
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sort(arr, arr + n);
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ll high = arr[n - 1], low = 0, mid, pos = 0;
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while (high >= low) {
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mid = (high + low) / 2;
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if (canbe(mid)) {
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low = mid + 1;
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pos = mid;
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}
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else {
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high = mid - 1;
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}
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}
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cout << pos << endl;
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}
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return 0;
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} |
