Submission #1274721

#	Time	Username	Problem	Language	Result	Execution time	Memory
1274721		AgentPengin	Mountains (NOI20_mountains)	C++20	100 / 100	119 ms	9972 KiB

Mountains

/**
 *    author:  AgentPengin ( Độc cô cầu bại )
 *    created: 23.12.2022 10:08:02
 *    too lazy to update time
**/
#include<bits/stdc++.h>

#define EL '\n'
#define fi first
#define se second
#define NAME "TASK"
#define ll long long
#define lcm(a,b) (a/gcd(a,b))*b
#define db(val) "["#val" = " << (val) << "] "
#define bend(v) (v).begin(),(v).end()
#define sz(v) (int)(v).size()
#define ex exit(0)
#define int ll

using namespace std;

const ll mod = 1e9 + 7;
const int inf = 0x1FFFFFFF;
const int MAXN = 3e5 + 5;

int n, h[MAXN], bit[2][MAXN];
vector<int> compress;

void update(int type, int x, int val) {
	for (;x < MAXN;x += x&-x) bit[type][x] += val;
}
int get(int type, int x) {
	int res = 0;
	if (x == 0) return 0;
	for (;x;x-=x&-x) res += bit[type][x];
	return res;
}

signed main() {
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    if (ifstream(NAME".inp")) {
        freopen(NAME".inp","r",stdin);
        freopen(NAME".out","w",stdout);
    }
    cin >> n;
    for (int i = 1;i <= n;i++) {
    	cin >> h[i];
		compress.push_back(h[i]);
    }
    sort(bend(compress));
    for (int i = 1;i <= n;i++) {
    	h[i] = lower_bound(bend(compress), h[i]) - compress.begin() + 1;
    }
    // for (int i = 1;i <= n;i++) cout << h[i] << " ";
    for (int i = n;i >= 3;i--) {
    	update(1, h[i], 1);
    }
    update(0, h[1], 1);
   	int ans = 0;
    for (int i = 2;i <= n - 1;i++) {
    	ans += get(0, h[i] - 1) * get(1, h[i] - 1);
    	update(0, h[i], 1);
    	update(1, h[i + 1], -1);
    }
    cout << ans;

    
    cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
    return 0;
}
// agent pengin wants to take apio (with anya-san)

Compilation message (stderr)

Mountains.cpp: In function 'int main()':
Mountains.cpp:42:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |         freopen(NAME".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
Mountains.cpp:43:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |         freopen(NAME".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