Submission #753278

#	Time	Username	Problem	Language	Result	Execution time	Memory
753278		bgnbvnbv	Group Photo (JOI21_ho_t3)	C++14	100 / 100	905 ms	744 KiB

Main

#include<bits/stdc++.h>
#define TASKNAME "codeforce"
#define pb push_back
#define pli pair<int,int>
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL);
using namespace std;
using ll=long long;
const ll maxN=2e5;
const ll inf=1e18;
const ll mod=1e9+7;
ll n,bit[3][maxN];
void update(ll t,ll i,ll v)
{
    while(i<=n)
    {
        bit[t][i]+=v;
        i+=(i&(-i));
    }
}
ll get(ll t,ll i)
{
    ll ans=0;
    while(i>0)
    {
        ans+=bit[t][i];
        i-=(i&(-i));
    }
    return ans;
}
ll a[maxN],pos[maxN],dp[maxN];
void solve()
{
    cin >> n;
    for(int i=1;i<=n;i++) cin >> a[i] ,pos[a[i]]=i;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=2;j++) fill(bit[j],bit[j]+n+1,0);
        ll sum1=0,sum2=0;
        for(int j=1;j<=i;j++) update(2,pos[j],1);
        dp[i]=inf;
        for(int j=i;j>=1;j--)
        {
            sum1+=get(1,n)-get(1,pos[j]);
            update(2,pos[j],-1);
            sum2+=get(2,n)-get(2,pos[j]);
            sum2-=get(1,pos[j]);
            update(1,pos[j],1);
            dp[i]=min(dp[i],dp[j-1]+sum1+sum2);
        }
    }
    cout << dp[n];
}
int main()
{
    fastio
    //freopen(TASKNAME".INP","r",stdin);
    //freopen(TASKNAME".OUT","w",stdout);
    solve();
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 20 / 20
• Subtask 5: 36 / 36