Submission #65875094

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Source Code Expand

#include <bits/stdc++.h>
#include <random>
#include <chrono>
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<double,double> pdd;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

template<typename T> void _do(T x){cerr<<x<<"\n";}
template<typename T,typename ...U> void _do(T x,U ...y){cerr<<x<<", ";_do(y...);}
#define dbg(...) cerr<<#__VA_ARGS__<<" = ";_do(__VA_ARGS__);

const int MOD1=1e9+7;
const int MOD2=998244353;
const ll INF=3e18;

ll fpow(ll a,ll b,ll m)
{
    if(!b) return 1;
    ll tmp=1;
    for(ll cur=a;b;b>>=1,cur=cur*cur%m) if(b&1) tmp=tmp*cur%m;
    return tmp;
}
ll inv(ll a,ll m) {return fpow(a,m-2,m);}

#define MottoHayaku ios::sync_with_stdio(false);cin.tie(0);
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define F first
#define S second
#define pb push_back
#define uni(c) c.resize(distance(c.begin(),unique(c.begin(),c.end())))
#define unisort(c) sort(c.begin(),c.end()),uni(c)

void solve()
{
    int n;
    cin>>n;
    vector<int> a(n);
    vector<int> type(n,0);
    rep(i,n) cin>>a[i];
    vector<int> pos;
    for(int i=1;i+1<n;i++)
    {
        if(a[i]>a[i-1]&&a[i]>a[i+1]) type[i]=1;
        if(a[i]<a[i-1]&&a[i]<a[i+1]) type[i]=2;
        if(type[i]!=0) pos.pb(i);
    }
    int sz=pos.size();
    ll ans=0;
    rep(i,sz-1)
    {
        int x=pos[i],y=pos[i+1];
        if(type[x]!=1||type[y]!=2) continue;

        int l=0,r=n-1;
        if(i-1>=0) l=pos[i-1];
        if(i+2<sz) r=pos[i+2];
        //dbg(l,x,y,r);
        ans+=1LL*max(0,x-l)*max(0,r-y);
    }
    cout<<ans<<"\n";
}

signed main()
{
    MottoHayaku
    int t;
    //cin>>t;
    t=1;
    while(t--)
    {
        solve();
    }
}

Submission Info

Judge Result