July Lunch Time : BINFUN

help
1

I am new in CodeChef and need some help in one of my solutions.

I have come up with below solution for the BINFUN problem from July Lunchtime:
https://www.codechef.com/viewsolution/36047870

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

ll highestBinDiff(ll numbers[], ll size);

int main() {
try{
ll tc = 0;
ll num = 0;

    cin >> tc;
    while(tc--){
        num = 0;
        cin >> num;
        ll arr[num];
        for(ll idx = 0; idx < num; idx++){
            cin >> arr[idx];
        }
        cout<<highestBinDiff(arr, num)<<endl;
    }
}catch(exception e){
    cout<<e.what()<<endl;
}
return 0;

}

ll highestBinDiff(ll numbers[], ll size)
{
ll maxBinDiff = 0;
unordered_map<ll, pair<ll, ll> > hashTable;

for(ll idx = 0; idx < size; idx++)
{
    ll num = numbers[idx];
    ll pos = log2(num) + 1;
    
    if(hashTable.find(pos) == hashTable.end()){
        hashTable[pos] = {num, num};
    }
    else{
        hashTable[pos].first = min(hashTable[pos].first, num);
        hashTable[pos].second = max(hashTable[pos].second, num);
    }
}

for(int i = 0; i < 30; i++)
{
    if(hashTable.find(i) == hashTable.end())
    {
        continue;
    }
    for(int j = 0; j < 30; j++)
    {
        if(hashTable.find(j) == hashTable.end())
        {
            continue;
        }
        
        ll x = hashTable[i].second;
        ll y = hashTable[j].first;
        
        ll diff = abs((x * pow(2, j) + y) - (y * pow(2, i) + x));
        maxBinDiff = max(diff, maxBinDiff);
    }
}

hashTable.clear();
return maxBinDiff;

}

Not being able to understand why it is not working. Will appreciate any leads.