Submission #1313392

#	Time	Username	Problem	Language	Result	Execution time	Memory
1313392		lev	Mountains (NOI20_mountains)	C++20	100 / 100	144 ms	23924 KiB

Mountains

#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define pii pair<int, int>
#define all(a) a.begin(), a.end()
using namespace std;

#ifdef LOCAL
#include "C:\Users\Dell\Downloads\template\template\icpc-notebook\Utilities\debug.h"
#else
#define debug(...) 42
#endif

const int mn = 5e5 + 5, mod = 1e9 + 7, inf = 2e9;

int n, a[mn];
vector <int> line[mn];

int bit[mn];

void add(int u, int val){
	while(u <= n){
		bit[u] += val;
		u += (u & -u);
	}
}

int get(int u){
	int r = 0;
	while(u){
		r += bit[u];
		u -= (u & -u);
	}
	return r;
}

int get(int l, int r){
	return get(r) - get(l - 1);
}

void solve() {
    cin >> n;
    vector <int> comp;
    // Compressed
    for(int i = 1; i <= n; i++){
    	cin >> a[i]; comp.push_back(a[i]);
    }
    sort(all(comp)); comp.erase(unique(all(comp)), comp.end());
    for(int i = 1; i <= n; i++){
    	a[i] = lower_bound(all(comp), a[i]) - comp.begin() + 1;
    	line[a[i]].push_back(i);
    }
    int res = 0;

    for(int i = 1; i <= (int)comp.size(); i++){
    	for(auto x : line[i]){
    		if(x > 1 && x < n) res += get(1, x - 1) * get(x + 1, n);
    	}
    	for(auto x : line[i]) add(x, 1);
    }
	cout << res << '\n';
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    #define task "Kawabata"
    if (fopen(task".INP", "r")) {
        freopen(task".INP", "r", stdin);
        freopen(task".OUT", "w", stdout);
    }
    int t = 1;
    // cin >> t;
    while (t--) solve();
    return 0;
}
// Don't wanna lose anymore T_T
// Never let me go - Kazuo Ishiguro

Compilation message (stderr)

Mountains.cpp: In function 'int main()':
Mountains.cpp:70:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |         freopen(task".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Mountains.cpp:71:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |         freopen(task".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• 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