Submission #526316

#	Time	Username	Problem	Language	Result	Execution time	Memory
526316		Carmel_Ab1	Mountains (NOI20_mountains)	C++17	100 / 100	471 ms	29400 KiB

Mountains

/*
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
 */
#include<bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>

//using namespace __gnu_pbds;
using namespace std;

typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int>vi;
typedef vector<vector<int>>vvi;
typedef vector<ll>vl;
typedef vector<vl> vvl;
typedef pair<int,int>pi;
typedef pair<ll,ll> pl;
typedef vector<pl> vpl;
typedef vector<ld> vld;
typedef pair<ld,ld> pld;
typedef vector<pi> vpi;

//typedef tree<ll, null_type, less_equal<ll>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
template<typename T> ostream& operator<<(ostream& os, vector<T>& a){os<<"[";for(int i=0; i<ll(a.size()); i++){os << a[i] << ((i!=ll(a.size()-1)?" ":""));}os << "]\n"; return os;}

#define all(x) x.begin(),x.end()
#define YES out("YES")
#define NO out("NO")
#define out(x){cout << x << "\n"; return;}
#define outfl(x){cout << x << endl;return;}
#define GLHF ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define print(x){for(auto ait:x) cout << ait << " "; cout << "\n";}
#define pb push_back
#define umap unordered_map

template<typename T1, typename T2> istream& operator>>(istream& is, pair<T1, T2>& p){is >> p.first >> p.second;return is;}
template<typename T1, typename T2> ostream& operator<<(ostream& os, pair<T1, T2>& p){os <<"" << p.first << " " << p.second << ""; return os;}
void usaco(string taskname){
    string fin = taskname + ".in";
    string fout = taskname + ".out";
    const char* FIN = fin.c_str();
    const char* FOUT = fout.c_str();
    freopen(FIN, "r", stdin);
    freopen(FOUT, "w", stdout);
}
template<typename T>
void read(vector<T>& v){
    int n=v.size();
    for(int i=0; i<n; i++)
        cin >> v[i];
}
template<typename T>
vector<T>UNQ(vector<T>a){
    vector<T>ans;
    for(T t:a)
        if(ans.empty() || t!=ans.back())
            ans.push_back(t);
    return ans;
}



void solve();
int main(){
    GLHF;
    int t=1;
    //cin >> t;
    while(t--)
        solve();
}
void compress(vl& a){
    vl s(a);
    sort(all(s));

    map<ll,ll>conv;
    int n=a.size();
    for(int i=0; i<n;i ++)
        conv[s[i]]=i;
    for(int i=0; i<n;i ++)
        a[i]=conv[a[i]];
}
struct seg{
    vl t;
    ll sz=1;
    seg(int n){
        sz=2*n;
        t.resize(sz);
    }
    void upd(ll i,ll v){
        t[i+=sz/2]+=v;
        while(i>1){
            t[i/2]=t[i]+t[i^1];
            i/=2;
        }
    }
    ll qur(ll l,ll r){
        ll ans=0;
        for(l+=sz/2,r+=sz/2 +1; l<r;l/=2,r/=2){
            if(l&1)ans+=t[l++];
            if(r&1)ans+=t[--r];
        }
        return ans;
    }
};

void solve() {
    ll n;
    cin >> n;
    vl a(n);
    read(a);

    compress(a);

    seg ST1(n+1),ST2(n+1);
    ll ans=0;

    for(int i=n-1; 0<=i; i--){
        ST2.upd(a[i],1);
        ST1.upd(a[i],ST2.qur(0,a[i]-1));
        ans+=ST1.qur(a[i]+1,n);
    }
    out(ans)
}

Compilation message (stderr)

Mountains.cpp: In function 'void usaco(std::string)':
Mountains.cpp:47:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |     freopen(FIN, "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~
Mountains.cpp:48:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |     freopen(FOUT, "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~

• Subtask 1: 2 / 2
• Subtask 2: 4 / 4
• Subtask 3: 9 / 9
• Subtask 4: 36 / 36
• Subtask 5: 28 / 28
• Subtask 6: 9 / 9
• Subtask 7: 12 / 12