Submission #1167708

#	Time	Username	Problem	Language	Result	Execution time	Memory
1167708		vibeduck	Mountains (NOI20_mountains)	C++20	64 / 100	183 ms	39740 KiB

Mountains

#include <bits/stdc++.h> 
using namespace std;

#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define int long long
#define all(x) (x).begin(), (x).end()

typedef long double ld;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<bool>> vvb;
typedef vector<vector<ll>> vvll;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef vector<char> vc;
typedef vector<vector<char>> vvc;
typedef map<int, int> mii;
typedef unordered_map<int, int> umii;

const int mod = 1e9 + 7;
const int inf = INTMAX_MAX;
const bool tc = false;

const int N = 2e5 + 5;
const int defval = 0;
int seg[4 * N];

ll segfunction(ll x, ll y) {
    return x + y;
}

ll query(int l, int r, int pos, int ql, int qr) {
    if (l > r) return defval;

    if (ql > r || l > qr) {
        return defval;
    }
    if (ql <= l && r <= qr) {
        return seg[pos];
    }
    int mid = (l + r) / 2;
    return segfunction(query(l, mid, pos * 2, ql, qr), query(mid + 1, r, pos * 2 + 1, ql, qr));
}

void update(int l, int r, int pos, int qpos, int qval) {
    if (l > r) return;

    if (l == r) {
        seg[pos] = qval;
        return;
    }

    int mid = (l + r) / 2;
    if (qpos <= mid) {
        update(l, mid, pos * 2, qpos, qval);
    } else {
        update(mid + 1, r, pos * 2 + 1, qpos, qval);
    }

    seg[pos] = segfunction(seg[pos * 2], seg[pos * 2 + 1]);
}

inline void solve() {
    int n; cin >> n;
    map<int, vi> pos; for (int i = 0; i < n; i++) {
        int x; cin >> x;
        pos[x].pb(i);
    }

    int ans = 0;
    for (auto it = pos.begin(); it != pos.end(); it++) {
        int v = it->first;
        vi p = it->second;
        for (auto &x : p) ans += query(0, n - 1, 1, 0, x - 1) * query(0, n - 1, 1, x + 1, n - 1);
        for (auto &x : p) update(0, n - 1, 1, x, 1);
    }    

    cout << ans << '\n';
}

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

signed main() {
    ios::sync_with_stdio(false);
    cout.tie(0);
    cin.tie(0);
    //setIO();

    int t = 1;
    if (tc) {
        cin >> t;
    }

    while (t--) {
        solve();
    }
}

Compilation message (stderr)

Mountains.cpp: In function 'void setIO(std::string)':
Mountains.cpp:91:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   91 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mountains.cpp:92:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 2
• Subtask 2: 0 / 4
• Subtask 3: 0 / 9
• Subtask 4: 36 / 36
• Subtask 5: 28 / 28
• Subtask 6: 0 / 9
• Subtask 7: 0 / 12