Submission #632492

#	Time	Username	Problem	Language	Result	Execution time	Memory
632492		shmad	Mountains (NOI20_mountains)	C++17	24 / 100	443 ms	46576 KiB

Mountains

#pragma GCC optimize("O3", "unroll-loops") // "Ofast" 	
#pragma GCC target("avx2", "bmi", "bmi2", "lzcnt", "popcnt") 

#include <bits/stdc++.h>

//#define int long long
#define vt vector
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define ff first
#define ss second
#define dbg(x) cerr << #x << " = " << x << '\n'
#define bit(x, i) ((x) >> (i) & 1)

using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vvt = vt< vt<int> >;

const int N = 1e6 + 5, mod = 1e9 + 7, B = 500;
const ll inf = 1e18 + 7, LIM = (1ll << 60);
const double eps = 1e-6;

int n;
map<int, int> m;
set<int> st;
int h[N];
ll t[4 * N];

void upd (int pos, int v = 1, int tl = 1, int tr = 	N) {
	if (tl == tr) {                                
		t[v]++;         
		return;
	}
	int tm = tl + tr >> 1;
	if (pos <= tm) upd(pos, v << 1, tl, tm);
	else upd(pos, v << 1 | 1, tm + 1, tr);
	t[v] = t[v << 1] + t[v << 1 | 1];
}

ll get (int l, int r, int v = 1, int tl = 1, int tr = N) {
	if (tl > r || tr < l) return 0ll;
	if (tl >= l && tr <= r) return t[v];
	int tm = tl + tr >> 1;
	ll a = get(l, r, v << 1, tl, tm);
	ll b = get(l, r, v << 1 | 1, tm + 1, tr);
	return (a + b);
}

ll l[N], r[N];

void solve () {
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> h[i], st.insert(h[i]);
	for (int i: st) m[i] = sz(m) + 1;
	for (int i = 1; i <= n; i++) h[i] = m[h[i]];
	for (int i = 1; i <= n; i++) l[i] = get(1, h[i] - 1), upd(h[i]);
	fill(t, t + 4 * N, 0);
	for (int i = n; i >= 1; i--) r[i] = get(1, h[i] - 1), upd(h[i]);
	ll ans = 0;
	for (int i = 1; i <= n; i++) ans += (l[i] * r[i]);
	cout << ans;
	cout << '\n';
}

bool testcases = 0;

signed main() {
	cin.tie(0) -> sync_with_stdio(0);
	int test = 1;
	if (testcases) cin >> test;
	for (int cs = 1; cs <= test; cs++) {
		solve();
	}
}

Compilation message (stderr)

Mountains.cpp: In function 'void upd(int, int, int, int)':
Mountains.cpp:36:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   36 |  int tm = tl + tr >> 1;
      |           ~~~^~~~
Mountains.cpp: In function 'll get(int, int, int, int, int)':
Mountains.cpp:45:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   45 |  int tm = tl + tr >> 1;
      |           ~~~^~~~

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