Submission #1135033

#	Time	Username	Problem	Language	Result	Execution time	Memory
1135033		steveonalex	Mountains (NOI20_mountains)	C++20	100 / 100	115 ms	12188 KiB

Mountains

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()

ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}

ll gcd(ll a, ll b){return __gcd(a, b);}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ll mask){return __builtin_ctzll(mask);}
int logOf(ll mask){return __lg(mask);}

mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}

template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }

template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }

template <class T>
    void printArr(T& container, string separator = " ", string finish = "\n"){
        for(auto item: container) cout << item << separator;
        cout << finish;
    }


template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }


struct FenwickTree{
    int n;
    vector<ll> a;

    FenwickTree(int _n){
        n = _n;
        a.resize(n+1);
    }

    void update(int i, ll v){
        while(i <= n){
            a[i] += v;
            i += LASTBIT(i);
        }
    }

    ll get(int i){
        ll ans = 0;
        while(i > 0){
            ans += a[i];
            i -= LASTBIT(i);
        }
        return ans;
    }

    ll get(int l, int r){return get(r) - get(l-1);}

    int binary_lift(ll x){
        int p = MASK(logOf(n)), idx =0;
        while(p > 0){
            if (idx + p <= n && x > a[idx + p]){
                idx += p;
                x -= a[idx];
            }
            p >>= 1;
        }
        return idx + 1;
    }
};


void solve(){
    int n; cin >> n;
    vector<ll> a(n);
    for(int i = 0; i<n; ++i) cin >> a[i];

    vector<ll> b = a; b.push_back(-1);
    remove_dup(b);
    for(ll &i: a) i = lower_bound(ALL(b), i) - b.begin();

    vector<int> pref(n), suff(n);

    int m = b.size() - 1;
    FenwickTree bit(m);
    for(int i = 0; i < n; ++i){
        bit.update(a[i], 1);
        pref[i] = bit.get(a[i] - 1);
    }
    bit = FenwickTree(m);
    for(int i = n-1; i>=0; --i){
        bit.update(a[i], 1);
        suff[i]= bit.get(a[i] - 1);
    }

    ll ans = 0;
    for(int i = 0; i < n; ++i) ans += 1LL * pref[i] * suff[i];

    cout << ans << "\n";
}

int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    clock_t start = clock();

    solve();

    cerr << "Time elapsed: " << clock() - start << "ms!\n";
    return 0;
}

• 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