POJ 1658

#include <iostream>
using namespace std;
int next(int* arr){
    bool p=true,q=true;
    int P=arr[1]-arr[0],Q=arr[1]/arr[0],i;
    for(i=2;i<4;++i) {
        if(arr[i]-arr[i-1]!=P)p=false;
        if(arr[i]/arr[i-1]!=Q)q=false;
    }
    return p?arr[3]+P:arr[3]*Q;
}

int main() {
    int N,arr[4],i;
    for(cin>>N;N--;){
        for(i=0;i<4;++i){
            cin>>arr[i];
            cout<<arr[i]<<" ";
        }
        cout<<next(arr)<<endl;
    }
    return 0;
}