Submission #1268145

#	Time	Username	Problem	Language	Result	Execution time	Memory
1268145		huyngodzz	Mountains (NOI20_mountains)	C++20	100 / 100	303 ms	14068 KiB

Mountains

///huynhocute123///
#include<bits/stdc++.h>
using namespace std;
#define S second
#define F first
#define pii pair<int,int>
#define piii pair<int,pair<int,int>>
#define pb push_back
#define FOR(i, a, b) for(int i = a; i <= b; ++i)
#define REP(i, a, b) for(int i = b; i >= a; --i)
#define ALL(v) v.begin(),v.end()
#define inp(name) if(fopen(name, "r")) freopen(name, "r", stdin);
#define out(name) if(fopen(name, "w")) freopen(name, "w", stdout);
//random_device rd;
//mt19937 rng(rd());
//#pragma GCC optimize ("O3")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("popcnt")
//#define int long long
const int MAX = 1e9+9;
const long long  MAXLL = 1e18+9;
const double pi = 3.14159265358979323846;
const double rad = 3.14159265358979323846 /180;
bool minimize(int &u, int v){
    if(v < u){
        u = v;
        return 1;
    }
    return 0;
}
bool maximize(int &u, int v){
    if(v > u){
        u = v;
        return 1;
    }
    return 0;
}
bool maximizell(long long &u, long long v){
    if(v > u){
        u = v;
        return 1;
    }
    return 0;
}
bool minimizell(long long &u, long long v){
    if(v < u){
        u = v;
        return 1;
    }
    return 0;
}
const int  mod = 1e9 + 7;
inline int fastPow(int a, int n){
    if(n == 0) return 1;
    int t = fastPow(a, n >> 1);
    t = 1ll * t * t % mod;
    if(n & 1) t = 1ll * t * a % mod;
    return t;
}
inline void Add(int& x ,int y){
    x += y;
    if(x >= mod)x -=mod;
}
inline void Sub(int& x, int y){
    x-= y;
    if(x < 0)x += mod;
}
const int maxN = 3 * 1e5  +99 ;
int n;
long long h[maxN], L[maxN] , R[maxN];
int st[4 * maxN];
void upd(int id ,int l ,int r, int pos ,int val){
    if(pos < l || pos > r)return;
    if(l == r){
        st[id] += val;
        return;
    }
    int mid = (l + r)/2;
    upd(id << 1 ,l ,mid ,pos ,val);
    upd(id << 1 | 1,mid + 1 ,r, pos ,val);
    st[id] = st[id << 1] + st[id << 1 | 1];
}
void init(int id ,int l ,int r){
    st[id] = 0;
    if(l == r)return;
    int mid = (l + r)/2;
    init(id << 1 , l ,mid);
    init(id << 1 | 1,mid + 1 ,r);
}
int get(int id ,int l ,int r ,int u ,int v){
    if(v < l || u > r)return 0;
    if(u <= l && r <= v)return st[id];
    int mid =(l + r)/2;
    return get(id << 1 ,l ,mid , u ,v) + get(id << 1 | 1 ,mid + 1, r, u ,v);
}
inline void solve(){
    cin >> n ;
    vector<long long > ar;
    FOR(i, 1, n){
        cin >> h[i];
        ar.pb(h[i]);
    }
    sort(ALL(ar));
    ar.erase(unique(ALL(ar)), ar.end());
    FOR(i, 1, n){
        h[i] = lower_bound(ALL(ar), h[i]) - ar.begin() + 1;
//        cout << h[i]  << " ";
    }
    init(1, 1, n);
    FOR(i, 1, n){
        int l = 1, r = h[i] - 1;
        if(l > r)L[i] = 0;
        else L[i] = get(1, 1, n ,l ,r);
        upd(1, 1, n, h[i], 1);
    }
    init(1, 1, n);
    REP(i, 1, n){
        int l = 1, r = h[i] - 1;
        if(l > r)R[i] = 0;
        else R[i] = get(1, 1, n ,l ,r);
        upd(1, 1, n, h[i], 1);
    }
    long long ans = 0;
    FOR(i, 1, n){
        ans = (ans + 1LL* L[i] * R[i] );
//        cout << L[i] * R[i] << '\n';
//        cout << L[i] << " " << i << " " << R[i] << '\n';
    }
    cout << ans;
}
#define NAME "task"
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    if(fopen(NAME".inp", "r")){
        freopen(NAME".inp", "r" ,stdin);
//        freopen(NAME".out", "w" ,stdout);
    }
    int tc = 1;
   // cin >> tc;
    while( tc-- )solve();


}

Compilation message (stderr)

Mountains.cpp: In function 'int main()':
Mountains.cpp:136:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  136 |         freopen(NAME".inp", "r" ,stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• 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