Submission #888926

#	Time	Username	Problem	Language	Result	Execution time	Memory
888926		vjudge1	Mountains (NOI20_mountains)	C++17	100 / 100	84 ms	17840 KiB

Mountains

/*
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,fma,bmi,bmi2,sse4.2,popcnt,lzcnt")
*/

#include <bits/stdc++.h>
#define taskname ""
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define i64 long long
#define pb push_back
#define ff first
#define ss second
#define isz(x) (int)x.size()
using namespace std;

const int mxN = 3e5 + 5;
const int mod = 1e9 + 7;
const i64 oo = 1e18;

struct FenwickTree {
    int n;
    vector<int> data;

    FenwickTree(int n) : n(n), data(n + 1) {}

    void update(int idx, int val) {
        for (; idx <= n; idx += idx & -idx)
            data[idx] += val;
    }

    int get(int idx) {
        int res = 0;
        for (; idx > 0; idx -= idx & -idx)
            res += data[idx];
        return res;
    }
};

int n;
i64 res, a[mxN];
vector<pair<i64, int>> v;

void solve() {
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
        v.emplace_back(a[i], i);
    }
    sort(all(v));

    FenwickTree fenw(n);
    for (int i = 0; i < n;) {
        int ptr = i;
        while (ptr < n && v[ptr].ff == v[i].ff) {
            int lt = fenw.get(v[ptr].ss), rt = i - lt;
            res += 1ll * lt * rt;
            ++ptr;
        }
        for (int j = i; j < ptr; ++j)
            fenw.update(v[j].ss, 1);
        i = ptr;
    }
    cout << res << endl;
}

signed main() {

#ifndef CDuongg
    if(fopen(taskname".inp", "r"))
        assert(freopen(taskname".inp", "r", stdin)), assert(freopen(taskname".out", "w", stdout));
#else
    freopen("bai3.inp", "r", stdin);
    freopen("bai3.out", "w", stdout);
    auto start = chrono::high_resolution_clock::now();
#endif

    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1; //cin >> t;
    while(t--) solve();

#ifdef CDuongg
   auto end = chrono::high_resolution_clock::now();
   cout << "\n"; for(int i = 1; i <= 100; ++i) cout << '=';
   cout << "\nExecution time: " << chrono::duration_cast<chrono::milliseconds> (end - start).count() << "[ms]" << endl;
   cout << "Check array size pls sir" << endl;
#endif

}

• 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