Submission #879986

#	Time	Username	Problem	Language	Result	Execution time	Memory
879986		cpptowin	Duathlon (APIO18_duathlon)	C++17	0 / 100	2 ms	4444 KiB

count_triplets

//cre:cpptowin
#pragma GCC optimize("O2")
#pragma GCC target("avx,avx2,fma")
#include<bits/stdc++.h>
#define db double
#define fo(i,d,c) for(int i=d;i<=c;i++)
#define fod(i,c,d) for(int i=c;i>=d;i--)
#define maxn 1000010
#define N 1010
#define fi first
#define se second
#define pb push_back
#define en cout<<"\n";
#define int long long
#define inf 1000000000
#define pii pair<int,int>
#define vii vector<pii>
#define eps 1e-9
#define bit(i,j) ((i>>j)&1)
#define offbit(i,j) (i^(1<<j))
#define onbit(i,j) (i|(j<<1))
#define vi vector<int>
#define vvi vector<vector<int>>
#define checkfile(FiLeNaMe) { if(fopen(FiLeNaMe".inp","r")) freopen(FiLeNaMe".inp","r",stdin),freopen(FiLeNaMe".out","w",stdout); }
template <typename T1, typename T2> bool minimize(T1 &a, T2 b)
{
    if (a > b)
    {
        a = b;
        return true;
    }
    return false;
}
template <typename T1, typename T2> bool maximize(T1 &a, T2 b)
{
    if (a < b)
    {
        a = b;
        return true;
    }
    return false;
}
using namespace std;
int par[maxn],tp[maxn];
int find(int u)
{
    return u==par[u]?u:par[u]=find(par[u]);
}
//int find(int u)
//{
//    return par[u]?par[u]=find(par[u]):u;
//}
pii a[maxn];
int n,res,cnt,arr[maxn];
main()
{
        freopen("DUATHLON.INP","r",stdin);
    freopen("DUATHLON.OUT","w",stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin>>n;
    fo(i,1,n) cin>>arr[i];
//    fo(i,1,n) cout<<arr[i]<<' ';
//    en;
    fo(i,1,n) a[i].fi=arr[i],a[i].se=i;
    sort(a+1,a+n+1,greater<pii>());
    fo(i,0,n+1) par[i]=i;
    tp[0]=0;
    tp[n+1]=n+1;
    fo(i,1,n) tp[i]=-1;
    bool ok=1;
    fo(i,2,n) if(arr[i]!=arr[i-1]) ok=0;
//    cout<<ok<<' ';
    if(ok)
    {
        cout<<0;return 0;
    }
    fo(i,1,n)
    {
        tp[a[i].se]=a[i].se;
//         cnt+=2;
//        if (tp[a[i].se-1]!=-1)
//        {
//            int x=find(a[i].se-1);
//            tp[a[i].se]=par[a[i].se]=x; cnt--;
//        }
//        if (tp[a[i].se+1]!=-1)
//        {
//            int x=find(a[i].se+1);
//            tp[a[i].se]=par[a[i].se]=x;
//            cnt--;
//        }
        if(a[i].se==1)
        {
            cnt++;
            if(tp[a[i].se+1]!=-1) cnt-=2;
        }
        else if(a[i].se==n)
        {
            cnt++;
            if(tp[a[i].se-1]!=-1) cnt-=2;
        }
        else if((tp[a[i].se+1]==-1||tp[a[i].se-1]==-1)&&(tp[a[i].se+1]+tp[a[i].se-1]!=-2)) ;
        else if(tp[a[i].se+1]==-1&&tp[a[i].se-1]==-1) cnt+=2;
        else if(tp[a[i].se+1]!=-1&&tp[a[i].se-1]!=-1) cnt-=2;
        if (a[i].fi > a[i+1].fi) res=max(res, cnt);
//        cout << cnt << ' ';
    }
//    en;
    cout<<res;
}

Compilation message (stderr)

count_triplets.cpp:55:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   55 | main()
      | ^~~~
count_triplets.cpp: In function 'int main()':
count_triplets.cpp:57:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   57 |         freopen("DUATHLON.INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
count_triplets.cpp:58:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   58 |     freopen("DUATHLON.OUT","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10