#include "bits/stdc++.h"
using namespace std;
#define ar array
typedef long long ll;
//~ #define int ll
const int INF = 1e9;
struct ST{
vector<int> min, max, p;
int N;
ST(){
N = 5e5 + 5;
min.resize(N << 2);
max.resize(N << 2);
p.resize(N << 2);
}
ST(int N): N(N) {
min.resize(N << 2);
max.resize(N << 2);
p.resize(N << 2);
}
void push(int x, int lx, int rx){
if(lx == rx) return;
min[x << 1] += p[x], max[x << 1] += p[x], p[x << 1] += p[x];
min[x << 1 | 1] += p[x], max[x << 1 | 1] += p[x], p[x << 1 | 1] += p[x];
p[x] = 0;
}
void add(int l, int r, int v, int lx, int rx, int x){
if(lx > r || rx < l) return;
if(lx >= l && rx <= r){
min[x] += v, max[x] += v, p[x] += v;
return;
}
int m = (lx + rx) >> 1;
push(x, lx, rx);
add(l, r, v, lx, m, x << 1), add(l, r, v, m + 1, rx, x << 1 | 1);
min[x] = ::min(min[x << 1], min[x << 1 | 1]);
max[x] = ::max(max[x << 1], max[x << 1 | 1]);
}
void add(int l, int r, int v){
add(l, r, v, 0, N, 1);
}
int Max(int l, int r, int lx, int rx, int x){
if(lx > r || rx < l) return -INF;
if(lx >= l && rx <= r) return max[x];
int m = (lx + rx) >> 1;
push(x, lx, rx);
return ::max(Max(l, r, lx, m, x << 1), Max(l, r, m + 1, rx, x << 1 | 1));
}
int Max(int l, int r){
return Max(l, r, 0, N, 1);
}
int Min(int l, int r, int lx, int rx, int x){
if(lx > r || rx < l) return INF;
if(lx >= l && rx <= r) return min[x];
int m = (lx + rx) >> 1;
push(x, lx, rx);
return ::min(Min(l, r, lx, m, x << 1), Min(l, r, m + 1, rx, x << 1 | 1));
}
int Min(int l, int r){
return Min(l, r, 0, N, 1);
}
};
signed main(){
ios::sync_with_stdio(0); cin.tie(0);
int n; cin >> n;
vector<int> a(n + 1);
for(int i=1;i<=n;i++){
cin >> a[i];
}
ST A, B;
vector<int> p(n);
iota(p.begin(), p.end(), 1);
sort(p.begin(), p.end(), [&](int i, int j){
if(a[i] != a[j]) return a[i] < a[j];
return i < j;
});
for(int i=1;i<=n;i++){
B.add(i, i, i);
A.add(i, i, -i);
}
int res = 0;
for(int i=0,j=0;i<n;){
vector<int> pos;
while(j < n && a[p[i]] == a[p[j]]){
pos.push_back(p[j]);
A.add(p[j], n, 2);
j++;
}
auto check = [&](int m){
for(int k=m - 1;k<(int)pos.size();k++){
int l = k - m + 1, r = k;
if(B.Max(pos[r], n) >= B.Min(0, pos[l] - 1) && A.Max(pos[r], n) >= A.Min(0, pos[l])) return true;
}
return false;
};
int l = 1, r = j - i;
while(l < r){
int m = (l + r + 1) >> 1;
if(check(m)) l = m;
else r = m - 1;
}
res = max(res, l);
while(i < j){
B.add(p[i], n, -2);
i++;
}
}
cout<<res<<"\n";
}
Compilation message
/usr/bin/ld: /tmp/ccVQUzvm.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/cc9Ffjlm.o:sequence.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/ccVQUzvm.o: in function `main':
grader.cpp:(.text.startup+0x2a4): undefined reference to `sequence(int, std::vector<int, std::allocator<int> >)'
collect2: error: ld returned 1 exit status
