Submission #1182067

#	Time	Username	Problem	Language	Result	Execution time	Memory
1182067		cpdreamer	Sequence (APIO23_sequence)	C++20	28 / 100	2096 ms	120440 KiB

sequence

#include "sequence.h"
#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;
        int 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 modification(node a,int v){
        return  {a.mind+v,a.maxd+v};
    }
    int operation_modifier(int a,int v){
        return a+v;
    }
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){
        if(lx>=r || rx<=l){
            return;
        }
        if(l<=lx && rx<=r){
            query[x]=modification(query[x],v);
            operation[x]= operation_modifier(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]=modification(merge(query[2*x+1],query[2*x+2]),operation[x]);
    }
    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){
        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 modification(merge(a,b),operation[x]);
    }
    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]]);
    int l=1,r=N;
    while(l<=r){
        int m=l+(r-l)/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);
        bool flag=false;
        for(auto u:d){
            int sz=(int)pos[u].size();
            for(int i=0;i+m-1<sz;i++){
                int x=pos[u][i];
                int y=pos[u][i+m-1];
                P<int,int>p1={tree.mind(0,x+1),tree.maxd(0,x+1)};
                P<int,int>p2={tree.mind(y,N+1),tree.maxd(y,N+1)};
                if(inter(p1,p2)){
                    flag=true;
                }
            }
            for(int i=0;i<sz;i++){
                tree.set(pos[u][i],N+1,-2);
            }
            for(int i=0;i+m-1<sz;i++){
                int x=pos[u][i];
                int y=pos[u][i+m-1];
                P<int,int>p1={tree.mind(0,x+1),tree.maxd(0,x+1)};
                P<int,int>p2={tree.mind(y,N+1),tree.maxd(y,N+1)};
                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;
}

Compilation message (stderr)

sequence.cpp: In function 'void file()':
sequence.cpp:13:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |     freopen("input.txt.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:14:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |     freopen("output.txt.txt", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 17 / 17
• Subtask 3: 0 / 7
• Subtask 4: 0 / 12
• Subtask 5: 0 / 13
• Subtask 6: 0 / 22
• Subtask 7: 0 / 18