#include "bits/stdc++.h"
#define int long long
#define dq deque<int>
using namespace std;
const long long INF = 1ll << 35;
const int N = 1e5 + 5;
int n, k, t, x[N];
dq L, R;
void ps(dq &v) {
v.push_front(0);
for (int i = 1; i < v.size(); i++) v[i] += v[i - 1];
}
array<int, 3> find(const dq &v) {
int mn = v[0];
for (int i = 1; i < v.size(); i++) {
int u = v[1];
mn = min(mn, u);
if (u >= v[0]) return {u, mn, 1};
}
return {0, 0, 0};
}
bool solve(array<dq, 2> v, int d = 0) {
if (v[0][0] + v[1][0] < 0 || v[1].back() + v[0].back() < 0) return false;
assert(d <= 1);
array<int, 3> A[2];
A[0] = find(v[0]);
A[1] = find(v[1]);
while (v[0].size() > 1 && v[1].size() > 1) {
//cout << v[0].size() << ' ' << v[1].size() << endl;
bool flag = false;
for (int k = 0; k < 2; k++) if (A[k][2]) {
if (v[k ^ 1][0] + A[k][1] >= 0) {
v[k].pop_front();
while (v[k][0] != A[k][0]) v[k].pop_front();
A[k] = find(v[k]);
flag = true;
}
}
if (flag) continue;
else if (A[0][2] && A[1][2]) return false;
if (!A[0][2] && !A[1][2]) {
//cout << "REVERSE SOLVE " << endl;
for (int k = 0; k < 2; k++) reverse(v[k].begin(), v[k].end());
return solve(v, d + 1);
}
else return false;
}
for (int k = 0; k < 2; k++) if (v[k].size() > 1) {
for (auto u: v[k]) if (u + v[1 ^ k][0] < 0) return false;
}
return true;
}
bool check(int O) {
int s = O * 2 * t;
dq l = L, r = R;
for (auto &u: l) u = s - u;
for (auto &u: r) u = s - u;
ps(l), ps(r);
array<dq, 2> v = {l, r};
/*
for (auto u: l) cout << u << ' ';
cout << endl;
for (auto u: r) cout << u << ' ';
cout << endl;
*/
return solve(v);
}
signed main() {
cin >> n >> k >> t;
k--;
for (int i = 0; i < n; i++) cin >> x[i];
for (int i = 0; i < k; i++)
L.push_back(x[i + 1] - x[i]);
reverse(L.begin(), L.end());
for (int i = k + 1; i < n; i++)
R.push_back(x[i] - x[i - 1]);
int l = -1, r = INF;
while (r - l > 1) {
int m = l + r >> 1;
if (check(m)) r = m;
else l = m;
}
cout << r << '\n';
return 0;
}
Compilation message
sparklers.cpp: In function 'void ps(std::deque<long long int>&)':
sparklers.cpp:12:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::deque<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
12 | for (int i = 1; i < v.size(); i++) v[i] += v[i - 1];
| ~~^~~~~~~~~~
sparklers.cpp: In function 'std::array<long long int, 3> find(const std::deque<long long int>&)':
sparklers.cpp:17:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::deque<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
17 | for (int i = 1; i < v.size(); i++) {
| ~~^~~~~~~~~~
sparklers.cpp: In function 'int main()':
sparklers.cpp:94:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
94 | int m = l + r >> 1;
| ~~^~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
212 KB |
Output is correct |
| 2 |
Correct |
1 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
212 KB |
Output is correct |
| 4 |
Runtime error |
1 ms |
468 KB |
Execution killed with signal 6 |
| 5 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
212 KB |
Output is correct |
| 2 |
Correct |
1 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
212 KB |
Output is correct |
| 4 |
Runtime error |
1 ms |
468 KB |
Execution killed with signal 6 |
| 5 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
212 KB |
Output is correct |
| 2 |
Correct |
1 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
212 KB |
Output is correct |
| 4 |
Runtime error |
1 ms |
468 KB |
Execution killed with signal 6 |
| 5 |
Halted |
0 ms |
0 KB |
- |
