HackerRank What’s Next? problem solution

In this HackerRank What’s Next? problem solution, we have given an array A, find integer array C and print its length on a new line then print the elements of array C as a single line of space-separated integers.

HackerRank What’s Next? problem solution in Python.

import sys

T = int(input().strip())
for _ in range(T):
    binary_A = []
    n = int(input().strip())
    A = list( map(int, input().strip().split()) )
    if n > 1:
        if n % 2 == 0:
            if n >= 4:
                if A[n - 3] == 1:
                    if A[n - 2] != 1:
                        A[n - 2] -= 1
                        A[n - 4] += 1
                        A[n - 3] += A[n - 1]
                        del A[n - 1]
                    else:
                        A[n - 4] += 1
                        A[n - 3] += A[n - 1]
                        del A[n - 2]
                        del A[n - 2]
                else:
                    A[n - 3] -= 1
                    A[n - 2] -= 1 
                    for _ in range(2):
                        A.insert(n - 2, 1)
                    A[n - 1] += A[n + 1]
                    del A[n + 1]
            else:
                if A[n - 2] == 1:
                    A[n - 1] += 1
                else:
                    A = [1, A[n - 1] + 1, A[n - 2] - 1]
                
        else:
            if A[n - 2] == 1:
                if A[n - 1] != 1:
                    A[n - 1] -= 1
                    A[n - 3] += 1
                else:
                    A[n - 3] += 1
                    del A[n - 1]
            else:
                A[n - 2] -= 1
                A[n - 1] -= 1
                for _ in range(2):
                    A.insert(n - 1, 1)
    else:
        A[0] -= 1
        for _ in range(2):
            A.insert(0, 1)
          
    if A[-1] == 0:
        del A[-1]
                
    print (len(A))
    print (' '.join(str(x) for x in A))
          

What’s Next? problem solution in Java.

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Scanner;

public class Solution {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        for (int i = 0; i < n; i++) {
            int len = scanner.nextInt();

            BigInteger[] a = new BigInteger[len];
            for (int j = 0; j < len; j++) {
                a[j] = new BigInteger(scanner.next());
            }
            BigInteger[] result = new NextNumber().nextNumber(a);
            System.out.println(result.length);
            for (int j = 0; j < result.length; j++) {
                System.out.print(result[j] + " ");
            }
            System.out.println();
        }
    }
}

class NextNumber {

    public BigInteger[] nextNumber(BigInteger[] binary) {
        ArrayList<BigInteger> result = new ArrayList<>();
        BigInteger[] dataToProcess;
        
        if (binary.length % 2 == 0) {
            for (int i = 0; i < binary.length - 2; i++) {
                result.add(binary[i]);
            }
            dataToProcess = new BigInteger[2];
            dataToProcess[0] = binary[binary.length - 1];
            dataToProcess[1] = binary[binary.length - 2];
        
        } else {
            for (int i = 0; i < binary.length - 1; i++) {
                result.add(binary[i]);
            }
            dataToProcess = new BigInteger[1];
            dataToProcess[0] = binary[binary.length - 1];
        }

        BigInteger[] secondPart = process(dataToProcess);
        if (result.size() > 0) {
            result.set(result.size() - 1, result.get(result.size() - 1).subtract(new BigInteger("1")));
        }
        for (int i = 0; i < secondPart.length; i++) {
            result.add(secondPart[i]);
        }
        result = removeZeros(result);
        BigInteger[] ret = new BigInteger[result.size()];
        for (int i = 0; i < result.size(); i++) {
            ret[i] = result.get(i);
        }
        return ret;
    }

    private ArrayList<BigInteger> removeZeros(ArrayList<BigInteger> result) {
        while (result.stream().anyMatch(x -> x.equals(new BigInteger("0")))) {
            int itemToRemove = -1;
            for (int i = 0; i < result.size(); i++) {
                if (result.get(i).equals(new BigInteger("0"))) {
                    itemToRemove = i;
                }
            }
            if (itemToRemove >= 0) {
                result.set(itemToRemove - 1, result.get(itemToRemove - 1).add(result.get(itemToRemove + 1)));
                result.remove(itemToRemove);
                result.remove(itemToRemove);
            }
        }
        return result;
    }

    public BigInteger[] process(BigInteger[] data) {
        BigInteger onesCount;
        BigInteger zerosCount;
        if (data.length == 2) {
            onesCount = data[1];
            zerosCount = data[0];
        } else {
            onesCount = data[0];
            zerosCount = new BigInteger("0");
        }
        ArrayList<BigInteger> resultData = new ArrayList<>();
        resultData.add(new BigInteger("1"));
        onesCount = onesCount.subtract(new BigInteger("1"));

        if (zerosCount.compareTo(new BigInteger("0")) > 0) {
            resultData.add(zerosCount.add(new BigInteger("1")));
        } else {
            resultData.add(new BigInteger("1"));
        }

        if (onesCount.compareTo(new BigInteger("0")) > 0) {
            resultData.add(onesCount);
        }
        BigInteger[] result = new BigInteger[resultData.size()];
        for (int i = 0; i < resultData.size(); i++) {
            result[i] = resultData.get(i);
        }
        return result;
    }
}

Problem solution in C++.

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
using namespace std;

typedef unsigned long long ul_t;

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int t;
    cin >> t;
    while(t--){
        int n;
        cin >> n;
        std::vector<ul_t> v(n);
        for(auto &a : v) cin >> a;

        ostringstream outOSS;
        if(n%2==1){
            if(n==1){
                outOSS << "1 1 ";
                if(v[0]>1) outOSS << v[0]-1 << " ";
            }
            else{
                for (int i = 0; i < n-3; ++i) outOSS << v[i] << " ";
                const ul_t x = v[n-3];
                const ul_t y = v[n-2];
                const ul_t z = v[n-1];

                if(y==1) outOSS << x+1 << " 1 ";
                else     outOSS << x << " " << y-1 << " 1 1 ";

                if(z>1)  outOSS << z-1 << " ";
            }
        }
        else if(n%2==0){
            if(n==2){
                outOSS << "1 ";
                if(v[0]>1) outOSS << v[1]+1 << " " << v[0]-1 << " ";
                else       outOSS << v[1]+1 << " ";
            }
            else{
                for (int i = 0; i < n-4; ++i) outOSS << v[i] << " ";
                const ul_t x = v[n-4];
                const ul_t y = v[n-3];
                const ul_t z = v[n-2];
                const ul_t q = v[n-1];

                if(y==1) outOSS << x+1 << " ";
                else     outOSS << x << " " << y-1 << " 1 ";

                if(z>1)  outOSS << q+1 << " " << z-1 << " ";
                else     outOSS << q+1 << " ";
            }
        }

        string s = outOSS.str();
        cout << count(s.begin(), s.end(),' ') << endl;
        cout << outOSS.str() << endl;
    }
    return 0;
}

Problem solution in C.

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

int main() {

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    int t,n;
    scanf("%d",&t);
    while(t--){
        scanf("%d",&n);
        unsigned long long A[n+2];
        for(int i=0;i<n;i++){
            scanf("%llu",&A[i]);           
        }
        if(n%2==1){
            
            if(n==1){
                if(A[0]>1){
                    
                    n+=2;
                    A[2]=A[0]-1; A[1]=1; A[0]=1;                    
                }
                else{
                    
                    n++;
                    A[1]=1;
                }
            }
            else if(A[n-2]==1){
                if(A[n-1]>1){
                   
                    A[n-1]-=1; A[n-3]+=1;                    
                }
                else{
                    
                    A[n-3]+=1;
                    n--;
                }
            }
            else{
                if(A[n-1]>1){
                    
                    n+=2;
                    A[n-1]=A[n-3]-1; A[n-2]=1; A[n-3]=1; A[n-4]--;              
                }
                else{
                   
                    n+=1;
                    A[n-3]--; A[n-2]=1; A[n-1]=1;
                }
            }
        }
        else{
           
            if(n==2){
                if(A[n-2]>1){
                    //110 -> 1001
                    n+=1;
                    A[2]=A[0]-1; A[1]+=1; A[0]=1; 
                }
                else{
     
                    A[1]++;
                }
            }
            else if(A[n-2]==1){                
                if(A[n-3]>1){
                               
                    A[n-1]++; A[n-3]--;
                }
                else{
                               
                    A[n-4]++;
                    A[n-3]=A[n-1]+1;
                    n-=2;
                }
            }
            else{
                if(A[n-3]>1){
                       
                    n++;
                    A[n-1]=A[n-3]-1;
                    A[n-2]++;
                    A[n-3]=1;
                    A[n-4]--;
                }
                else{
                       
                    A[n-4]++;
                    A[n-3]=A[n-1]+1;
                    A[n-2]--;
                    n--;
                }                
            }
        }
        printf("%dn",n);
        for(int i=0;i<n;i++){
            printf("%llu ",A[i]);           
        }
        printf("n");       
    }
    
    return 0;
}