Submission #750596

#	Time	Username	Problem	Language	Result	Execution time	Memory
750596		arnold518	Sequence (APIO23_sequence)	C++17	100 / 100	852 ms	65292 KiB

sequence

#include "sequence.h"
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 5e5;

int N, A[MAXN+10];
vector<int> V[MAXN+10];

struct Node
{
    int sum, minv, maxv;
    Node() : sum(0), minv(0), maxv(0) {}
    Node(int x) : sum(x), minv(min(x, 0)), maxv(max(x, 0)) {}
};

Node operator + (const Node &p, const Node &q)
{
    Node ret;
    ret.sum=p.sum+q.sum;
    ret.minv=min(p.minv, p.sum+q.minv);
    ret.maxv=max(p.maxv, p.sum+q.maxv);
    return ret;
}

struct SEG
{
    Node tree[MAXN*4+10];

    void update(int node, int tl, int tr, int p, int q)
    {
        if(p<tl || tr<p) return;
        if(tl==tr)
        {
            tree[node]=Node(q);
            return;   
        }
        int mid=tl+tr>>1;
        if(p<=mid) update(node*2, tl, mid, p, q);
        else update(node*2+1, mid+1, tr, p, q);
        tree[node]=tree[node*2]+tree[node*2+1];
    }
    Node query(int node, int tl, int tr, int l, int r)
    {
        if(l<=tl && tr<=r) return tree[node];
        if(r<tl || tr<l) return Node();
        int mid=tl+tr>>1;
        return query(node*2, tl, mid, l, r)+query(node*2+1, mid+1, tr, l, r);
    }
}seg;

int sequence(int _N, std::vector<int> _A)
{
    N=_N;
    for(int i=1; i<=N; i++) A[i]=_A[i-1];

    for(int i=1; i<=N; i++) V[i].push_back(0);
    for(int i=1; i<=N; i++) V[A[i]].push_back(i);
    for(int i=1; i<=N; i++) V[i].push_back(N+1);
    for(int i=1; i<=N; i++) seg.update(1, 1, N, i, 1);

    int ans=0;
    for(int i=1; i<=N; i++)
    {
        for(auto it : V[i]) seg.update(1, 1, N, it, 0);
        for(auto it : V[i-1]) seg.update(1, 1, N, it, -1);
        vector<pii> VV;
        int t=0;
        for(int j=1; j<V[i].size(); j++)
        {
            Node nd=seg.query(1, 1, N, V[i][j-1]+1, V[i][j]-1);
            VV.push_back({t+nd.minv, t+nd.maxv});
            t+=nd.sum;
        }
        //for(auto it : VV) printf("%d %d\n", it.first, it.second);
        for(int j=0; j<VV.size(); j++)
        {
            int lo=-1, hi=j;
            while(lo+1<hi)
            {
                int mid=lo+hi>>1;
                if(VV[j].second+j<VV[mid].first || VV[j].first-j>VV[mid].second) lo=mid;
                else hi=mid;
            }
            ans=max(ans, j-hi);
            VV[j].first+=j; VV[j].second-=j;
            if(j)
            {
                VV[j].first=min(VV[j].first, VV[j-1].first);
                VV[j].second=max(VV[j].second, VV[j-1].second);
            }
        }
        //printf("-> %d\n", i);
    }
    return ans;
}

Compilation message (stderr)

sequence.cpp: In member function 'void SEG::update(int, int, int, int, int)':
sequence.cpp:42:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   42 |         int mid=tl+tr>>1;
      |                 ~~^~~
sequence.cpp: In member function 'Node SEG::query(int, int, int, int, int)':
sequence.cpp:51:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   51 |         int mid=tl+tr>>1;
      |                 ~~^~~
sequence.cpp: In function 'int sequence(int, std::vector<int>)':
sequence.cpp:73:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   73 |         for(int j=1; j<V[i].size(); j++)
      |                      ~^~~~~~~~~~~~
sequence.cpp:80:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   80 |         for(int j=0; j<VV.size(); j++)
      |                      ~^~~~~~~~~~
sequence.cpp:85:27: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   85 |                 int mid=lo+hi>>1;
      |                         ~~^~~

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