HackerEarth Maximizing expressions problem solution

In this HackerEarth Maximizing expressions problem solution You are given three arrays A, B, and C. All the three arrays consist of N integers.

You must perform the following operation on each index exactly one time:

Convert(i): Select a positive value D such that Ci & D = D, and update Bi = Bi xor D.

Here, xor and & denotes the bitwise XOR operation and bitwise AND operation.

You are required to maximize the following expression:

S = sigma(n, i = 1) Ai xor Bi

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 100009;
ll n, m, x, y, z;

ll ara1[maxn], ara2[maxn], ara3[maxn];

bool getBit(ll val, ll pos)
{
    return (bool)(val & (1LL << pos));
}

int main()
{

    cin >> n;
    for(ll i = 1; i <= n; i++) scanf("%lld", &ara1[i]);
    for(ll i = 1; i <= n; i++) scanf("%lld", &ara2[i]);
    for(ll i = 1; i <= n; i++) scanf("%lld", &ara3[i]);
    ll anss = 0;

    for(ll i = 1; i <= n; i++){

        ll tmp = 0;
        bool flg = false;

        for(ll j = 0; j < 30; j++){
            ll mx1 = getBit(ara1[i], j) ^ getBit(ara2[i], j);
            ll mx2 = getBit(ara1[i], j) ^ getBit(ara2[i], j) ^ getBit(ara3[i], j);
            tmp += (1LL << j) * max(mx1, mx2);
            if(mx2 && getBit(ara3[i], j)) flg = true;
        }

        if(!flg){
            ll lstSetbit = 0;
            while(getBit(ara3[i], lstSetbit) == 0) lstSetbit++;
            if(getBit(tmp, lstSetbit) == 0) assert(false);

            tmp -= (1LL << lstSetbit);
        }

        anss += tmp;

    }

    cout << anss << endl;

    return 0;
}