# Prime Permutation code failing at 2 test case START100 HELP

• I’m finding 2 prime numbers which sum to ‘n’. Then printing the permutation such that difference is always one of those 2 selected numbers.
``````#include <bits/stdc++.h>
using namespace std;
#define f(a,b,n) for(int a=b; a<n; a++)
#define speed                         \
ios_base::sync_with_stdio(false); \
cin.tie(NULL);                    \
cout.tie(NULL);
#define mod 1000000007

const int sz = 100001;
bool prime[sz];
vector<int> v= {2};
void find(){
f(i,2,sz){
if(i&1){
int root = floor(sqrt(i));
bool p = true;
for(int j=3; j<=root+1; j+=2){
if(i%j==0){
p = prime[i] = false;
break;
}
}
if(p){
prime[i] = true;
v.push_back(i);
}
}
else{
prime[i] = (i==2);
}
}
}

void solve(){
int n; cin>>n;
bool flag = true;
for(int i : v){
if(i>=n){
break;
}
int rem = n-i;
if(prime[rem]){
flag = false;
// cout<<i<<" "<<rem<<endl;
int j = i+1;
while(j<=n){
cout<<(j++)<<" ";
}
j = 1;
while(j<=i){
cout<<(j++)<<" ";
}
cout<<endl;
break;
}
}
if(flag){
cout<<-1<<endl;
}
}

int main(){
speed;
int cases;
cin>>cases;
find();
while(cases--){
solve();
}
return 0;
}

``````

You print -1 for n = 11, but there is in fact a valid permutation for that.

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