Submission #1687126

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Source Code Expand

#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define spair(p) cout<<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout<<" "<<kbrni;cout<<endl
#define smap(m) cout<<#m<<":";each(kbrni,m)cout<<" {"<<kbrni.first<<":"<<kbrni.second<<"}";cout<<endl

using namespace std;

typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<double> vd;
typedef vector<P> vp;

const int MAX_N = 200005;

int pos[MAX_N];

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    rep(i,n){
        int a;
        cin >> a;
        --a;
        pos[a] = i;
    }
    set<int> st;
    ll ans = 0;
    rep(i,n){
        auto it = st.lower_bound(pos[i]);
        ll l,r;
        if(it == st.end()){
            if(it == st.begin()){
                ans += (ll)(i+1)*(pos[i]+1)*(n-pos[i]);
            }else{
                it--;
                l = *it;
                ans += (ll)(i+1)*(pos[i]-l)*(n-pos[i]);
            }
        }else if(it == st.begin()){
            r = *it;
            ans += (ll)(i+1)*(pos[i]+1)*(r-pos[i]);
        }else{
            r = *it;
            it--;
            l = *it;
            ans += (ll)(i+1)*(pos[i]-l)*(r-pos[i]);
        }
        st.insert(pos[i]);
    }
    cout << ans << endl;
    return 0;
}

Submission Info

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