#include "sequence.h"
#include <bits/stdc++.h>
#define SZ(s) ((int) ((s).size()))
using namespace std;
// Lazy Segment Tree, copied from AtCoder {{{
// Source: https://github.com/atcoder/ac-library/blob/master/atcoder/lazysegtree.hpp
// Doc: https://atcoder.github.io/ac-library/master/document_en/lazysegtree.html
//
// Notes:
// - Index of elements from 0
// - Range queries are [l, r-1]
// - composition(f, g) should return f(g())
//
// Tested:
// - https://oj.vnoi.info/problem/qmax2
// - https://oj.vnoi.info/problem/lites
// - (range set, add, mult, sum) https://oj.vnoi.info/problem/segtree_itmix
// - (range add (i-L)*A + B, sum) https://oj.vnoi.info/problem/segtree_itladder
// - https://atcoder.jp/contests/practice2/tasks/practice2_l
// - https://judge.yosupo.jp/problem/range_affine_range_sum
int ceil_pow2(int n) {
int x = 0;
while ((1U << x) < (unsigned int)(n)) x++;
return x;
}
template<
class S, // node data type
S (*op) (S, S), // combine 2 nodes
S (*e) (), // identity element
class F, // lazy propagation tag
S (*mapping) (F, S), // apply tag F on a node
F (*composition) (F, F), // combine 2 tags
F (*id)() // identity tag
>
struct LazySegTree {
LazySegTree() : LazySegTree(0) {}
explicit LazySegTree(int n) : LazySegTree(vector<S>(n, e())) {}
explicit LazySegTree(const vector<S>& v) : _n((int) v.size()) {
log = ceil_pow2(_n);
size = 1 << log;
d = std::vector<S>(2 * size, e());
lz = std::vector<F>(size, id());
for (int i = 0; i < _n; i++) d[size + i] = v[i];
for (int i = size - 1; i >= 1; i--) {
update(i);
}
}
// 0 <= p < n
void set(int p, S x) {
assert(0 <= p && p < _n);
p += size;
for (int i = log; i >= 1; i--) push(p >> i);
d[p] = x;
for (int i = 1; i <= log; i++) update(p >> i);
}
// 0 <= p < n
S get(int p) {
assert(0 <= p && p < _n);
p += size;
for (int i = log; i >= 1; i--) push(p >> i);
return d[p];
}
// Get product in range [l, r-1]
// 0 <= l <= r <= n
// For empty segment (l == r) -> return e()
S prod(int l, int r) {
assert(0 <= l && l <= r && r <= _n);
if (l == r) return e();
l += size;
r += size;
for (int i = log; i >= 1; i--) {
if (((l >> i) << i) != l) push(l >> i);
if (((r >> i) << i) != r) push((r - 1) >> i);
}
S sml = e(), smr = e();
while (l < r) {
if (l & 1) sml = op(sml, d[l++]);
if (r & 1) smr = op(d[--r], smr);
l >>= 1;
r >>= 1;
}
return op(sml, smr);
}
S all_prod() {
return d[1];
}
// 0 <= p < n
void apply(int p, F f) {
assert(0 <= p && p < _n);
p += size;
for (int i = log; i >= 1; i--) push(p >> i);
d[p] = mapping(f, d[p]);
for (int i = 1; i <= log; i++) update(p >> i);
}
// Apply f on all elements in range [l, r-1]
// 0 <= l <= r <= n
void apply(int l, int r, F f) {
assert(0 <= l && l <= r && r <= _n);
if (l == r) return;
l += size;
r += size;
for (int i = log; i >= 1; i--) {
if (((l >> i) << i) != l) push(l >> i);
if (((r >> i) << i) != r) push((r - 1) >> i);
}
{
int l2 = l, r2 = r;
while (l < r) {
if (l & 1) all_apply(l++, f);
if (r & 1) all_apply(--r, f);
l >>= 1;
r >>= 1;
}
l = l2;
r = r2;
}
for (int i = 1; i <= log; i++) {
if (((l >> i) << i) != l) update(l >> i);
if (((r >> i) << i) != r) update((r - 1) >> i);
}
}
// Binary search on SegTree to find largest r:
// f(op(a[l] .. a[r-1])) = true (assuming empty array is always true)
// f(op(a[l] .. a[r])) = false (assuming op(..., a[n]), which is out of bound, is always false)
template <bool (*g)(S)> int max_right(int l) {
return max_right(l, [](S x) { return g(x); });
}
template <class G> int max_right(int l, G g) {
assert(0 <= l && l <= _n);
assert(g(e()));
if (l == _n) return _n;
l += size;
for (int i = log; i >= 1; i--) push(l >> i);
S sm = e();
do {
while (l % 2 == 0) l >>= 1;
if (!g(op(sm, d[l]))) {
while (l < size) {
push(l);
l = (2 * l);
if (g(op(sm, d[l]))) {
sm = op(sm, d[l]);
l++;
}
}
return l - size;
}
sm = op(sm, d[l]);
l++;
} while ((l & -l) != l);
return _n;
}
// Binary search on SegTree to find smallest l:
// f(op(a[l] .. a[r-1])) = true (assuming empty array is always true)
// f(op(a[l-1] .. a[r-1])) = false (assuming op(a[-1], ..), which is out of bound, is always false)
template <bool (*g)(S)> int min_left(int r) {
return min_left(r, [](S x) { return g(x); });
}
template <class G> int min_left(int r, G g) {
assert(0 <= r && r <= _n);
assert(g(e()));
if (r == 0) return 0;
r += size;
for (int i = log; i >= 1; i--) push((r - 1) >> i);
S sm = e();
do {
r--;
while (r > 1 && (r % 2)) r >>= 1;
if (!g(op(d[r], sm))) {
while (r < size) {
push(r);
r = (2 * r + 1);
if (g(op(d[r], sm))) {
sm = op(d[r], sm);
r--;
}
}
return r + 1 - size;
}
sm = op(d[r], sm);
} while ((r & -r) != r);
return 0;
}
private:
int _n, size, log;
vector<S> d;
vector<F> lz;
void update(int k) {
d[k] = op(d[2*k], d[2*k+1]);
}
void all_apply(int k, F f) {
d[k] = mapping(f, d[k]);
if (k < size) lz[k] = composition(f, lz[k]);
}
void push(int k) {
all_apply(2*k, lz[k]);
all_apply(2*k+1, lz[k]);
lz[k] = id();
}
};
// }}}
// SegTree examples {{{
// Examples: Commonly used SegTree ops: max / min / sum
using S = pair<int,int>;
S op(S left, S right) {
return {
min(left.first, right.first),
max(left.second, right.second),
};
}
S e() {
return {
1000111000,
-1000111000,
};
}
using F = int;
S mapping(F f, S s) {
return {
s.first + f,
s.second + f,
};
}
F composition(F f, F g) {
return f + g;
}
F id() { return 0; }
// using STMax = SegTree<int, MaxSegTreeOp::op, MaxSegTreeOp::e>;
// using STMin = SegTree<int, MinSegTreeOp::op, MinSegTreeOp::e>;
// }}}
vector<int> cached_geq_right, cached_geq_left, cached_g_right, cached_g_left;
void initCache(int n, const vector<int>& a, const vector<vector<int>>& ids) {
cached_geq_right.resize(n);
cached_geq_left.resize(n);
cached_g_right.resize(n);
cached_g_left.resize(n);
LazySegTree<S, op, e, F, mapping, composition, id> st_geq(n + 1), st_g(n + 1);
// st_geq: >= median: +1; < median: -1
// st_g: > median: +1; <= median: -1
st_geq.set(0, {0, 0});
st_g.set(0, {0, 0});
for (int median = 0; median <= n; ++median) {
if (median == 0) {
for (int i = 1; i <= n; ++i) {
st_geq.set(i, {i, i});
st_g.set(i, {i, i});
}
} else {
for (int i : ids[median]) {
st_g.apply(i, n+1, -2);
}
for (int i : ids[median-1]) {
st_geq.apply(i, n+1, -2);
}
}
for (int i : ids[median]) {
cached_geq_right[i] = st_geq.prod(i, n+1).second;
cached_geq_left[i] = st_geq.prod(0, i).first;
cached_g_right[i] = st_g.prod(i, n+1).first;
cached_g_left[i] = st_g.prod(0, i).second;
}
}
}
bool can(int n, int eq, const vector<int>& a, const vector<vector<int>>& ids) {
for (int median = 0; median <= n; median++) {
if (SZ(ids[median]) < eq) continue;
for (int ix = 0, iy = eq-1; iy < SZ(ids[median]); ++ix, ++iy) {
int x = ids[median][ix];
int y = ids[median][iy];
// find [l, r]:
// - l <= x < y <= r
// - less + eq >= greater
// - greater + eq >= less
// - eq >= greater - less >= -eq
// - eq >= (greater(r) - less(r)) - (greater(l-1) - less(l-1)) >= -eq
int max_val = cached_geq_right[y] - cached_geq_left[x];
int min_val = cached_g_right[y] - cached_g_left[x];
if (max_val * (int64_t) min_val <= 0) return true;
}
}
return false;
}
int sequence(int n, std::vector<int> a) {
// ids from 1
a.insert(a.begin(), 0);
vector<vector<int>> ids(n + 1);
for (int i = 1; i <= n; ++i) {
ids[a[i]].push_back(i);
}
initCache(n, a, ids);
int left = 1, right = n, res = 1;
while (left <= right) {
int mid = (left + right) / 2;
if (can(n, mid, a, ids)) {
res = mid;
left = mid + 1;
} else {
right = mid - 1;
}
}
return res;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
212 KB |
Output is correct |
| 3 |
Runtime error |
1 ms |
340 KB |
Execution killed with signal 6 |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
212 KB |
Output is correct |
| 3 |
Runtime error |
1 ms |
340 KB |
Execution killed with signal 6 |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
212 KB |
Output is correct |
| 2 |
Correct |
1044 ms |
58160 KB |
Output is correct |
| 3 |
Correct |
1035 ms |
58168 KB |
Output is correct |
| 4 |
Correct |
957 ms |
50732 KB |
Output is correct |
| 5 |
Correct |
1057 ms |
57260 KB |
Output is correct |
| 6 |
Correct |
1014 ms |
57100 KB |
Output is correct |
| 7 |
Correct |
972 ms |
50776 KB |
Output is correct |
| 8 |
Correct |
941 ms |
50916 KB |
Output is correct |
| 9 |
Runtime error |
1058 ms |
103784 KB |
Execution killed with signal 6 |
| 10 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
212 KB |
Output is correct |
| 2 |
Correct |
963 ms |
51112 KB |
Output is correct |
| 3 |
Correct |
917 ms |
51612 KB |
Output is correct |
| 4 |
Correct |
975 ms |
51612 KB |
Output is correct |
| 5 |
Correct |
992 ms |
51100 KB |
Output is correct |
| 6 |
Correct |
972 ms |
51572 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1253 ms |
63892 KB |
Output is correct |
| 2 |
Correct |
1273 ms |
63876 KB |
Output is correct |
| 3 |
Correct |
1239 ms |
63312 KB |
Output is correct |
| 4 |
Correct |
1220 ms |
63312 KB |
Output is correct |
| 5 |
Correct |
1261 ms |
59968 KB |
Output is correct |
| 6 |
Correct |
1274 ms |
59972 KB |
Output is correct |
| 7 |
Correct |
1108 ms |
58776 KB |
Output is correct |
| 8 |
Correct |
1087 ms |
58464 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
212 KB |
Output is correct |
| 3 |
Runtime error |
1 ms |
340 KB |
Execution killed with signal 6 |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
212 KB |
Output is correct |
| 3 |
Runtime error |
1 ms |
340 KB |
Execution killed with signal 6 |
| 4 |
Halted |
0 ms |
0 KB |
- |
