#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int INF = (int) 1e9 + 1e6 + 123;
const ll LINF = (ll) 1e18 + 1e9 + 123;
#define rep(i, s, t) for (auto i = (s); i < (t); ++(i))
#define per(i, s, t) for (auto i = (s); i >= (t); --(i))
#define sz(x) ((int)(x).size())
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
bool mini(auto &x, const auto &y) {
if (y < x) {
x = y;
return 1;
}
return 0;
}
bool maxi(auto &x, const auto &y) {
if (y > x) {
x = y;
return 1;
}
return 0;
}
void run();
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
run();
return 0;
}
const int N = (int) 1e5 + 123;
ll t;
ll calc_need(ll c, vector<ll> people, ll bonus=0) {
if (sz(people) == 0) {
return 0;
}
ll left = -1;
for (ll &x : people) {
x = max(0LL, x - bonus);
}
ll right = people[0];
while (right - left > 1) {
ll mid = (left + right) / 2;
ll have_time = mid;
vector<ll> tmp = people;
ll sum = 0;
while (sz(tmp)) {
if (sum + have_time >= tmp.back() - sum - have_time) {
sum += have_time;
have_time = 2 * t * c;
tmp.pop_back();
} else {
break;
}
}
if (sz(tmp)) {
left = mid;
} else {
right = mid;
}
}
return right;
}
bool check(vector<ll> x, int k, ll c, ll bonus=0) {
int n = sz(x);
vector<ll> right_people;
per(i, n - 1, k + 1) {
right_people.push_back((x[i] - x[k]) * 2);
}
ll need_right = calc_need(c, right_people, bonus);
vector<ll> left_people;
rep(i, 0, k) {
left_people.push_back((x[k] - x[i]) * 2);
}
ll need_left = calc_need(c, left_people, bonus);
return need_left + need_right <= 2 * t * c;
}
bool wow(vector<ll> x, int k, ll c) {
if (check(x, k, c)) {
return true;
}
if (k == 0) {
return false;
}
ll to = x[k] - t * c;
if (x[k - 1] + t * c < to) {
return false;
}
{
ll bonus = 2 * t * c - (x[k] - x[k - 1]);
vector<ll> w = x;
for (ll &it : w) {
it *= 2;
}
ll moved = x[k] - x[k - 1];
int tk = k - 1;
w[tk] = max(0LL, w[tk] + moved);
w.erase(w.begin() + k);
per(i, tk - 1, 0) {
w[i] += moved;
w[i] = min(w[i], w[i + 1]);
}
rep(i, tk + 1, sz(w)) {
w[i] -= moved;
w[i] = max(w[i], w[i - 1]);
}
vector<ll> right_people;
per(i, sz(w) - 1, tk + 1) {
right_people.push_back(w[i] - w[tk]);
}
ll need_right = calc_need(c, right_people, 0);
vector<ll> left_people;
rep(i, 0, k) {
left_people.push_back(w[tk] - w[i]);
}
ll need_left = calc_need(c, left_people, 0);
if (need_left + need_right <= 2 * t * c + bonus) {
return true;
}
}
x.erase(x.begin() + k);
k--;
x[k] = max(0LL, to);
per(i, k - 1, 0) {
x[i] += t * c;
x[i] = min(x[i], x[i + 1]);
}
rep(i, k + 1, sz(x)) {
x[i] -= t * c;
x[i] = max(x[i], x[i - 1]);
}
return wow(x, k, c);
}
void run() {
int n, k;
cin >> n >> k >> t;
k--;
vector<ll> x(n);
rep(i, 0, n) {
cin >> x[i];
}
ll result = LINF;
rep(iter, 0, 2) {
ll left = 0;
ll right = (x[n - 1] / t) + 1;
while (right - left > 1) {
ll mid = (left + right) / 2;
if (wow(x, k, mid)) {
right = mid;
} else {
left = mid;
}
}
mini(result, right);
k = n - 1 - k;
vector<ll> tmp(n);
rep(i, 0, n) {
tmp[i] = x[n - 1] - x[i];
}
reverse(all(tmp));
rep(i, 0, n) {
x[i] = tmp[i];
}
}
cout << result << "\n";
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
248 KB |
Output is correct |
| 2 |
Correct |
2 ms |
360 KB |
Output is correct |
| 3 |
Correct |
2 ms |
560 KB |
Output is correct |
| 4 |
Correct |
2 ms |
560 KB |
Output is correct |
| 5 |
Correct |
3 ms |
560 KB |
Output is correct |
| 6 |
Correct |
2 ms |
560 KB |
Output is correct |
| 7 |
Incorrect |
2 ms |
560 KB |
Output isn't correct |
| 8 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
248 KB |
Output is correct |
| 2 |
Correct |
2 ms |
360 KB |
Output is correct |
| 3 |
Correct |
2 ms |
560 KB |
Output is correct |
| 4 |
Correct |
2 ms |
560 KB |
Output is correct |
| 5 |
Correct |
3 ms |
560 KB |
Output is correct |
| 6 |
Correct |
2 ms |
560 KB |
Output is correct |
| 7 |
Incorrect |
2 ms |
560 KB |
Output isn't correct |
| 8 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
248 KB |
Output is correct |
| 2 |
Correct |
2 ms |
360 KB |
Output is correct |
| 3 |
Correct |
2 ms |
560 KB |
Output is correct |
| 4 |
Correct |
2 ms |
560 KB |
Output is correct |
| 5 |
Correct |
3 ms |
560 KB |
Output is correct |
| 6 |
Correct |
2 ms |
560 KB |
Output is correct |
| 7 |
Incorrect |
2 ms |
560 KB |
Output isn't correct |
| 8 |
Halted |
0 ms |
0 KB |
- |
