Submission #632498

#TimeUsernameProblemLanguageResultExecution timeMemory
632498shmadMountains (NOI20_mountains)C++17
100 / 100
822 ms76336 KiB
    #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<ll, int> m;
    set<ll> st;
    ll h[N], 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;
    	vt<int> p(n + 1, 0), s(n + 2, 0);
    	for (int i = 1; i <= n; i++) cin >> h[i], st.insert(h[i]);
    	for (int i: st) m[i] = sz(m);
    	for (int i = 1; i <= n; i++) h[i] = m[h[i]];
    	ll ans = 0;
    	for (int i = 1; i <= n; i++) {
    		p[i] = p[i - 1] + (h[i] == 0);
    		l[i] = (h[i] == 1 ? p[i - 1] : get(0, h[i] - 1));
    		upd(h[i]);
    	}
    	fill(t, t + 4 * N, 0);
    	for (int i = n; i >= 1; i--) {
    		s[i] = s[i + 1] + (h[i] == 0);
    		r[i] = (h[i] == 1 ? s[i + 1] : get(0, h[i] - 1));
    		upd(h[i]);
    	}
    	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(long long int, long long int, long long int, long long int)':
Mountains.cpp:35:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   35 |      int tm = tl + tr >> 1;
      |               ~~~^~~~
Mountains.cpp: In function 'll get(long long int, long long int, long long int, long long int, long long int)':
Mountains.cpp:44:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   44 |      int tm = tl + tr >> 1;
      |               ~~~^~~~
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