CSES - Datatähti Open 2021 - Results
Submission details
Task:Sorting
Sender:kostia244
Submission time:2021-01-30 17:13:54 +0200
Language:C++17
Status:READY
Result:0
Feedback
groupverdictscore
#10
#20
Test results
testverdicttimegroup
#10.01 s1, 2details
#20.01 s2details
#3ACCEPTED0.01 s1, 2details
#4ACCEPTED0.01 s1, 2details

Compiler report

input/code.cpp: In member function 'void fen::add(int)':
input/code.cpp:9:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(; pos < a.size(); pos += pos&-pos) a[pos]++;
         ~~~~^~~~~~~~~~

Code

#include<bits/stdc++.h>
#define all(x) x.begin(), x.end()
using namespace std;
using ll = long long;
struct fen {
	vector<int> a;
	fen(int n) : a(n+1) {}
	void add(int pos) {
		for(; pos < a.size(); pos += pos&-pos) a[pos]++;
	}
	int get(int pos) {
		int res = 0;
		for(; pos; pos -= pos&-pos) res += a[pos];
		return res;
	}
};
int main() {
	cin.tie(0)->sync_with_stdio(0);
	int t;
	cin >> t;
	while(t--) {
		int n;
		cin >>n;
		vector<int> a(n);
		fen f(n);
		ll inv = 0;
		for(auto &i : a) {
			cin >> i;
			inv += f.get(i);
			f.add(i);
		};
		inv = n*1ll*(n-1)/2 - inv;
		if(n < 4) {
			inv = inv != 0;
		}
		if(n == 4) {
			inv = inv != 0 && inv != 2;
		}
		cout << (inv%2?"NO":"YES") << '\n';
	}
}

Test details

Test 1

Group: 1, 2

Verdict:

input
153
1
1
2
1 2
...

correct output
YES
YES
NO
NO
NO
...

user output
YES
YES
NO
NO
NO
...

Test 2

Group: 2

Verdict:

input
1000
59
35 29 32 50 11 15 9 21 19 45 2...

correct output
YES
NO
YES
NO
YES
...

user output
YES
NO
YES
NO
YES
...

Test 3

Group: 1, 2

Verdict: ACCEPTED

input
720
6
1 6 4 5 2 3
6
6 3 2 1 5 4
...

correct output
YES
NO
NO
NO
YES
...

user output
YES
NO
NO
NO
YES
...

Test 4

Group: 1, 2

Verdict: ACCEPTED

input
1000
8
7 4 2 8 6 3 5 1
8
3 8 2 7 5 4 6 1
...

correct output
NO
NO
YES
NO
YES
...

user output
NO
NO
YES
NO
YES
...