#include <bits/stdc++.h>
using namespace std;
#define fwd(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) fwd(i, 0, n)
#define all(X) X.begin(), X.end()
#define sz(X) int(size(X))
#define pb push_back
#define eb emplace_back
#define st first
#define nd second
using pii = pair<int, int>;
using vi = vector<int>;
using ll = long long;
using ld = long double;
#ifdef LOC
auto SS = signal(6, [](int) {
*(int *)0 = 0;
});
# define DTP(x, y) \
auto operator<<(auto &o, auto a)->decltype(y, o) { \
o << "("; \
x; \
return o << ")"; \
}
DTP(o << a.st << ", " << a.nd, a.nd);
DTP(for (auto i : a) o << i << ", ", all(a));
void dump(auto... x) {
((cerr << x << ", "), ...) << '\n';
}
# define deb(x...) cerr << setw(4) << __LINE__ << ":[" #x "]: ", dump(x)
#else
# define deb(...) 0
#endif
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
int n;
cin >> n;
vi a(2 * n + 1);
a[2 * n] = 1e9;
rep(i, n) {
cin >> a[i];
a[i + n] = a[i];
}
const int LG = 22;
vector<array<int, LG> > jmp(2 * n + 1);
rep(i, LG) jmp[2 * n][i] = 2 * n;
vi stk = {2 * n};
for (int i = 2 * n - 1; i >= 0; i--) {
while (!stk.empty() && a[stk.back()] <= a[i]) {
stk.pop_back();
}
jmp[i][0] = stk.back();
for (int j = 1; j < LG; j++) {
jmp[i][j] = jmp[jmp[i][j - 1]][j - 1];
}
stk.push_back(i);
}
int ans = 0;
rep(l, n) {
int r = l + n;
int jumps = 0;
int cur = l;
for (int j = LG - 1; j >= 0; j--) {
if (jmp[cur][j] < r) {
cur = jmp[cur][j];
jumps += 1 << j;
}
}
ans = max(ans, jumps + 1);
}
cout << ans << '\n';
#ifdef LOCF
cout.flush();
cerr << "- - - - - - - - -\n";
(void)!system(
"grep VmPeak /proc/$PPID/status | sed s/....kB/\' MB\'/1 >&2"); // 4x.kB
// ....kB
#endif
return 0;
}
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 | #include <bits/stdc++.h> using namespace std; #define fwd(i, a, n) for (int i = (a); i < (n); i++) #define rep(i, n) fwd(i, 0, n) #define all(X) X.begin(), X.end() #define sz(X) int(size(X)) #define pb push_back #define eb emplace_back #define st first #define nd second using pii = pair<int, int>; using vi = vector<int>; using ll = long long; using ld = long double; #ifdef LOC auto SS = signal(6, [](int) { *(int *)0 = 0; }); # define DTP(x, y) \ auto operator<<(auto &o, auto a)->decltype(y, o) { \ o << "("; \ x; \ return o << ")"; \ } DTP(o << a.st << ", " << a.nd, a.nd); DTP(for (auto i : a) o << i << ", ", all(a)); void dump(auto... x) { ((cerr << x << ", "), ...) << '\n'; } # define deb(x...) cerr << setw(4) << __LINE__ << ":[" #x "]: ", dump(x) #else # define deb(...) 0 #endif int32_t main() { cin.tie(0)->sync_with_stdio(0); int n; cin >> n; vi a(2 * n + 1); a[2 * n] = 1e9; rep(i, n) { cin >> a[i]; a[i + n] = a[i]; } const int LG = 22; vector<array<int, LG> > jmp(2 * n + 1); rep(i, LG) jmp[2 * n][i] = 2 * n; vi stk = {2 * n}; for (int i = 2 * n - 1; i >= 0; i--) { while (!stk.empty() && a[stk.back()] <= a[i]) { stk.pop_back(); } jmp[i][0] = stk.back(); for (int j = 1; j < LG; j++) { jmp[i][j] = jmp[jmp[i][j - 1]][j - 1]; } stk.push_back(i); } int ans = 0; rep(l, n) { int r = l + n; int jumps = 0; int cur = l; for (int j = LG - 1; j >= 0; j--) { if (jmp[cur][j] < r) { cur = jmp[cur][j]; jumps += 1 << j; } } ans = max(ans, jumps + 1); } cout << ans << '\n'; #ifdef LOCF cout.flush(); cerr << "- - - - - - - - -\n"; (void)!system( "grep VmPeak /proc/$PPID/status | sed s/....kB/\' MB\'/1 >&2"); // 4x.kB // ....kB #endif return 0; } |
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