Help me in solving STRNG problem

help
,
1

My issue

output is coming wrong

My code

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

int main() {
	int t,v;
	cin>>t;
	while(t--){
	    
	int n=0;cin>>n;
	vector<int>v(n);
	for(int i=0;i<n;++i)
	{
	    cin>>v[i];
	}
	vector<int>prefix(n);
	prefix[0]=v[0];
	for(int i=1;i<n;++i)
	{
	    prefix[i]=(prefix[i-1],v[i]);
	}
	vector<int>suffix(n);
	suffix[n-1]=v[n-1];
	for(int i=n-2;i>=0;--i)
	{
	    suffix[i]=(suffix[i+1],v[i]);
	}
	int strong =0;
	for(int i=0;i<n;++i)
	{
	    if(i==0 && suffix[i]>i){
	strong++;
	        
	    }
	 else if((prefix[i-1],suffix[i+1])>1)
	 {
	     strong++;
	 }
	}
	cout<<strong<<'\n';
	}
}

Learning course: Number theory
Problem Link: CodeChef: Practical coding for everyone

2

@krajgor23
your logic is correct but implementation is wrong .
plzz refer the following solution for better understanding.

#include <bits/stdc++.h>

using namespace std;


int main() {
	// your code goes here
	int t;
	cin>>t;
	while(t--)
	{
	    int n,i,x;
	    vector<int> v;
	    cin>>n;
	    for(i=0;i<n;i++)
	    {
	        cin>>x;
	        v.push_back(x);
	    }
	    int gcd;
	    gcd=v[0];
	    vector<int> pre;
	    for(i=0;i<n;i++)
	    {
	        gcd=__gcd(gcd,v[i]);
	        pre.push_back(gcd);
	    }
	    gcd=v[n-1];
	    vector<int> suf;
	    for(i=n-1;i>=0;i--)
	    {
	        gcd=__gcd(gcd,v[i]);
	        suf.push_back(gcd);
	    }
	    reverse(suf.begin(),suf.end());
	    int res=0;
	    for(i=1;i<n-1;i++)
	    {
	        if(__gcd(pre[i-1],suf[i+1])!=1)
	        {
	            res++;
	        }
	    }
	    if(pre[n-2]!=1)
	    {
	        res++;
	    }
	    if(suf[1]!=1)
	    {
	        res++;
	    }
	    cout<<res<<endl;
	}
	return 0;
}