| # | 제출 시각 | 아이디 | 문제 | 언어 | 결과 | 실행 시간 | 메모리 |
|---|---|---|---|---|---|---|---|
| 1182122 | cpdreamer | 서열 (APIO23_sequence) | C++20 | 0 ms | 0 KiB |
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define P pair
#define F first
#define all(v) v.begin(),v.end()
#define V vector
#define pb push_back
#define S second
const ll MOD=(ll)1e9+7;
void file() {
freopen("input.txt.txt", "r", stdin);
freopen("output.txt.txt", "w", stdout);
}
struct segtree {
private:
struct node {
int mind, maxd;
};
node single(int v) {
return {v, v};
}
node neutral = {INT_MAX, INT_MIN};
node merge(node a, node b) {
return {min(a.mind, b.mind), max(a.maxd, b.maxd)};
}
node apply(node a, int v) {
return {a.mind + v, a.maxd + v};
}
void push(int x, int lx, int rx) {
if (rx - lx == 1 || operation[x] == 0) return;
int v = operation[x];
query[2 * x + 1] = apply(query[2 * x + 1], v);
query[2 * x + 2] = apply(query[2 * x + 2], v);
operation[2 * x + 1] += v;
operation[2 * x + 2] += v;
operation[x] = 0;
}
public:
int size;
V<node> query;
V<int> operation;
void init(int n) {
size = 1;
while (size < n) size *= 2;
query.assign(2 * size, neutral);
operation.assign(2 * size, 0);
}
void build(V<int> &a, int x, int lx, int rx) {
if (rx - lx == 1) {
if (lx < (int)a.size()) {
query[x] = single(a[lx]);
}
return;
}
int m = (lx + rx) / 2;
build(a, 2 * x + 1, lx, m);
build(a, 2 * x + 2, m, rx);
query[x] = merge(query[2 * x + 1], query[2 * x + 2]);
}
void build(V<int> &a) {
build(a, 0, 0, size);
}
void set(int l, int r, int v, int x, int lx, int rx) {
push(x, lx, rx);
if (lx >= r || rx <= l) return;
if (l <= lx && rx <= r) {
query[x] = apply(query[x], v);
operation[x] += v;
return;
}
int m = (lx + rx) / 2;
set(l, r, v, 2 * x + 1, lx, m);
set(l, r, v, 2 * x + 2, m, rx);
query[x] = merge(query[2 * x + 1], query[2 * x + 2]);
}
void set(int l, int r, int v) {
set(l, r, v, 0, 0, size);
}
node calc(int l, int r, int x, int lx, int rx) {
push(x, lx, rx);
if (rx <= l || lx >= r) return neutral;
if (l <= lx && rx <= r) return query[x];
int m = (lx + rx) / 2;
node a = calc(l, r, 2 * x + 1, lx, m);
node b = calc(l, r, 2 * x + 2, m, rx);
return merge(a, b);
}
int mind(int l, int r) {
return calc(l, r, 0, 0, size).mind;
}
int maxd(int l, int r) {
return calc(l, r, 0, 0, size).maxd;
}
};
bool inter(P<int,int>a,P<int,int>b){
if(a.F>b.F)
swap(a,b);
return a.S>=b.F;
}
int f(int N,V<int>A){
V<int>a(N+1);
V<int>occ(N+1);
V<V<int>>pos(N+1);
set<int>st;
for(int i=1;i<=N;i++) {
a[i] = A[i - 1];
occ[a[i]]++;
pos[a[i]].pb(i);
st.insert(a[i]);
}
V<int>d;
for(auto u:st)
d.pb(u);
V<int>b=a;
sort(all(b));
int ans=max(occ[b[(N+1)/2]],occ[b[(N+2)/2]]);
V<int>vp(N+1);
vp[0]=0;
for(int i=1;i<=N;i++){
vp[i]=vp[i-1]+1;
}
segtree tree;
tree.init(N);
tree.build(vp);
for(auto u:d){
V<P<P<int,int>,P<int,int>>>q;
int sz=(int)pos[u].size();
for(int i=0;i<sz;i++){
int mnl=tree.mind(0,pos[u][i]+1);
int mxl=tree.maxd(0,pos[u][i]+1);
int mnr=tree.mind(pos[u][i],N+1);
int mxr=tree.maxd(pos[u][i],N+1);
q.pb({{mnl,mxl},{mnr,mxr}});
}
int l=1,r=N;
while(l<=r){
int m=l+(r-l)/2;
bool flag=false;
for(int i=0;i+m-1<sz;i++){
P<int,int>p1={q[i].F.F,q[i].F.S};
P<int,int>p2={q[i+m-1].S.F,q[i+m-1].S.S};
if(inter(p1,p2))
flag=true;
}
if(flag){
ans=max(ans,m);
l=m+1;
}
else
r=m-1;
}
for(int i=0;i<sz;i++){
tree.set(pos[u][i],N+1,-2);
}
q.clear();
for(int i=0;i<sz;i++){
int mnl=tree.mind(0,pos[u][i]+1);
int mxl=tree.maxd(0,pos[u][i]+1);
int mnr=tree.mind(pos[u][i],N+1);
int mxr=tree.maxd(pos[u][i],N+1);
q.pb({{mnl,mxl},{mnr,mxr}});
}
l=1,r=N;
while(l<=r){
int m=l+(r-l)/2;
bool flag=false;
for(int i=0;i+m-1<sz;i++){
P<int,int>p1={q[i].F.F,q[i].F.S};
P<int,int>p2={q[i+m-1].S.F,q[i+m-1].S.S};
if(inter(p1,p2))
flag=true;
}
if(flag){
ans=max(ans,m);
l=m+1;
}
else
r=m-1;
}
}
return ans;
}
int sequence(int N, std::vector<int> &A) {
int ans=f(N,A);
return ans;
}
void solve() {
int n;
cin>>n;
V<int>A(n);
for(int i=0;i<n;i++){
cin>>A[i];
}
cout<<sequence(n,A)<<endl;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
file();
solve();
}