Weird Error that i dont understand

help
1

So i am getting a sigcont error on the code that i have written and i think that is the reason for my solution not being accepted.

here is the submission link: CodeChef

Here is the code:

#include
using namespace std;

int main() {
long long T;
cin>>T;
while(T–){
long long x;
cin>>x;
if(x<=4){
cout<<-1;
}else{
if(x%2 == 0){
for(long i =1;i<x/2+1;i++){
cout<<i<<" “<<x/2+i<<” “;
}
}else{
for(long i = 1;i<x/2+1;i++){
cout<<i<<” “<<x/2+1+i<<” “;
}
cout<<x/2+1;
}
}
cout<<”\n";
}
}

could someone help me understand whats the problem here??

2

This is because you’re not considering the test case N = 4. When N = 4, your answer should be 3 1 4 2 not -1.

Here’s my solution:

#include <iostream>
#include <vector>
using namespace std; 

int main() {
	// your code goes here
	int t;
	cin >> t;
	while (t--) {
	    int N;
	    cin >> N;
	    if (N < 4) {
	        cout << -1 << "\n";
	    }
	    else if (N == 4) {
	        cout << 3 <<" "<< 1 <<" "<< 4 <<" "<< 2 << "\n";
	    }
	    else {
	        int middle;
	        if (N%2 == 0) {
	            middle = N / 2;
	        }
	        else {
	            middle = (N + 1) / 2;
	        }
	        int a = 1;
	        int b = middle + 1;
	        vector<int> v1;
	        for (int i = 0; i < middle; i++) {
	            v1.push_back(a);
	            if (v1.size() != N) {
	                v1.push_back(b);
	            }
	            a += 1;
	            b += 1;
	        }
	        for (auto itr = v1.begin(); itr != v1.end(); ++itr)
	        cout << *itr << " ";
	    }
	}
	return 0;
}

Before this my solution I was also doing the same mistake, we should think about edge test cases more carefully. All the best :+1: