Facebook Interview Question for Android Engineers


Team: London office
Country: India
Interview Type: Phone Interview




Comment hidden because of low score. Click to expand.
1
of 1 vote

public static void main(String[] args)
  {
    int arr1[] = {0};
	int arr2[] = {0, 1};
	int arr3[] = {0, 1, 0};
	int arr4[] = {1, 0};
	int arr5[] = {1, 0, 0};
	int arr6[] = {0, 1, 0, 2};
	int arr7[] = {1, 0, 0, 2};

    System.out.println(Arrays.toString(moveAndPrint(arr1)));
    System.out.println(Arrays.toString(moveAndPrint(arr2)));
    System.out.println(Arrays.toString(moveAndPrint(arr3)));
    System.out.println(Arrays.toString(moveAndPrint(arr4)));
    System.out.println(Arrays.toString(moveAndPrint(arr5)));
    System.out.println(Arrays.toString(moveAndPrint(arr6)));
    System.out.println(Arrays.toString(moveAndPrint(arr7)));
    
  }
  
  public static int[] moveAndPrint(int[] arr)
  {
    if (arr == null) return null;
    
    int i = 0, j = arr.length-1;
    
	while (i < j) {
		while (arr[j] == 0)
			j--;

		while (arr[i] != 0)
			i++;

      	// Swap elements
      	if (i < j) {
        	arr[i] = arr[j];
        	arr[j] = 0;
        }
	}

    return arr;
  }

- Tejas April 09, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

Use two pointers, one for iterating through the array and another one for maintaining the last seen zero index. Every time you see a non-zero index, swap it with the previous seen zero index. Simple solution in Python

Solution:

def moveZeroes(arr):
    i, j = 0, 0
    while i < len(arr):
        if arr[i] != 0:
            arr[i], arr[j] = arr[j], arr[i]
            j += 1
        i += 1
    return arr

Test code:

print(moveZeroes([0, 3, 1, 0, 2, 6, 7, 0])) # Output: [3, 1, 2, 6, 7, 0, 0, 0]
print(moveZeroes([0,0,1,0,0])) # Output: [1, 0, 0, 0, 0]
print(moveZeroes([0,3])) # Output: [3, 3]

- prudent_programmer March 28, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

def none_zero(array):
j = 0
for i in range(len(array)):
if array[i] != 0:
array[j] = array[i]
j += 1
return array[:j]

print none_zero([1,0,3,2,6,7,1,0,10,0])

- two pointers method is good enough March 29, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

def none_zero(array):
  j = 0
  for i in range(len(array)):
    if array[i] != 0:
      array[j] = array[i]
      j += 1
  return array[:j]

print none_zero([1,0,3,2,6,7,1,0,10,0])

- two pointers March 29, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

def none_zero(array):
  j = 0
  for i in range(len(array)):
    if array[i] != 0:
      array[j] = array[i]
      j += 1
  return array[:j]

print none_zero([1,0,3,2,6,7,1,0,10,0])

- two pointers March 29, 2018 | Flag Reply
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0
of 0 vote

import java.util.*;
public class HelloWorld{

public static void main(String []args){
int[] arr = {1, -2, 5, 6, 0, 1,0,3,0,0,0, 6,8,9};
for(Integer a: moveAndPrint(arr)){
System.out.println(a);
}
}

private static int[] moveAndPrint(int[] arr){
int i =0;
for(int j=arr.length-1; i<j; j--){
if(arr[i] != 0){
if(arr[j] == 0){
arr[j] = arr[i];
arr[i] = 0;
i++;
}
}
}
System.out.println(arr.length - i);
return arr;
}
}

- Anonymous March 29, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

import java.util.*;
public class HelloWorld{

public static void main(String []args){
int[] arr = {1, -2, 5, 6, 0, 1,0,3,0,0,0, 6,8,9};
for(Integer a: moveAndPrint(arr)){
System.out.println(a);
}
}

private static int[] moveAndPrint(int[] arr){
int i =0;
for(int j=arr.length-1; i<j; j--){
if(arr[i] != 0){
if(arr[j] == 0){
arr[j] = arr[i];
arr[i] = 0;
i++;
}
}
}
System.out.println(arr.length - i);
return arr;
}
}

- dda March 29, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

import java.util.*;
public class HelloWorld{

     public static void main(String []args){
         int[] arr = {1, -2, 5, 6, 0, 1,0,3,0,0,0, 6,8,9};
         for(Integer a: moveAndPrint(arr)){
             System.out.println(a);
         }
     }
     
     private static int[] moveAndPrint(int[] arr){
         int i =0;
         for(int j=arr.length-1; i<j; j--){
             if(arr[i] != 0){
                 if(arr[j] == 0){
                     arr[j] = arr[i];
                     arr[i] = 0;
                     i++;
                 } 
             }
         }
         System.out.println(arr.length - i);
         return arr;
     }

}

- Anonymous March 29, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

Using above test inputs. 

public static void main(String[] args){
        int[] arr = {0, 3, 1, 0, 2, 6, 7, 0};
        System.out.println(Arrays.toString(nonZero(arr)));
        
        int[] arr1 = {0, 0, 1, 0, 0, 0};
        System.out.println(Arrays.toString(nonZero(arr1)));
        
        int[] arr2 = {0, 3};
        System.out.println(Arrays.toString(nonZero(arr2)));
        
    }
    
    public static int[] nonZero(int[] arr) {
        int i=0;
        int length = arr.length;
        int result[] = new int[length];
        int j=0;
        while(i<length){
            if(arr[i] == 0) {
                i++;
            }else{
                result[j++] = arr[i++];
            }
        }
        return result;
    }

Results
[3, 1, 2, 6, 7, 0, 0, 0]
[1, 0, 0, 0, 0, 0]
[3, 0]

- silvimasss March 29, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

public class MoveZerosToLast {
	public static void main(String[] args) {
		int[] a = { 1, 9, 8, 4, 0, 0, 2, 7, 0, 6, 0, 9 };
		int j = 0;
		for (int i = 0; i < a.length; i++) {
			if (a[i] != 0) {
				if (i == j) {
					j++;
				} else {
					a[j] = a[i];
					a[i] = 0;
					j++;
				}
			}
		}
		System.out.println(Arrays.toString(a));
	}
}

- Bushan SC March 30, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

from sys import stdin
array = stdin.readline().strip().split()
ceros=0
for i in array:
  if i == '0':
    ceros += 1
  else:
    print i,
print '0 ' * ceros

- Anonymous March 31, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

from sys import stdin
array = stdin.readline().strip().split()
ceros=0
for i in array:
  if i == '0':
    ceros += 1
  else:
    print i,
print '0 ' * ceros

- NicolasZON March 31, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

public static void main(String[] args)
  {
    int arr1[] = {0};
	int arr2[] = {0, 1};
	int arr3[] = {0, 1, 0};
	int arr4[] = {1, 0};
	int arr5[] = {1, 0, 0};
	int arr6[] = {0, 1, 0, 2};
	int arr7[] = {1, 0, 0, 2};

    System.out.println(Arrays.toString(moveAndPrint(arr1)));
    System.out.println(Arrays.toString(moveAndPrint(arr2)));
    System.out.println(Arrays.toString(moveAndPrint(arr3)));
    System.out.println(Arrays.toString(moveAndPrint(arr4)));
    System.out.println(Arrays.toString(moveAndPrint(arr5)));
    System.out.println(Arrays.toString(moveAndPrint(arr6)));
    System.out.println(Arrays.toString(moveAndPrint(arr7)));
    
  }
  
  public static int[] moveAndPrint(int[] arr)
  {
    if (arr == null) return null;
    
    int i = 0, j = arr.length-1;
    
	while (i < j) {
		while (arr[j] == 0)
			j--;

		while (arr[i] != 0)
			i++;

      	// Swap elements
      	if (i < j) {
        	arr[i] = arr[j];
        	arr[j] = 0;
        }
	}

    return arr;

}

- Tejas April 09, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

int nonzero(vector<int> & arr)
{
	int n = arr.size(), i = 0, j = n - 1;
	while (i < j)
	{
		while (j>=0 && arr[j] != 0)
			j--;
		while (i<n && arr[i] == 0)
			i++;
		if (i>j||j<0||i>=n)
			return n-(j + 1);
		iter_swap(arr.begin() + i, arr.begin() + j);
	}
}

- aman.bansal4u May 22, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

a=[3,2,0,3,1,3,0,0,1,0]
b=[None]*len(a)
def movezeroo(a):
i=0
j=len(a)-1
k=0
print(b)
while i<=len(a)-1:
if a[i]!=0:
print(i, j,'ok')
b[j]=a[i]
print(i,j)
i=i+1
j=j-1
else:
b[k]=a[i]
k=k+1
i=i+1
print(b)

- Harsh October 04, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

a=[3,2,0,3,1,3,0,0,1,0]
b=[None]*len(a)
def movezeroo(a):
    i=0
    j=len(a)-1
    k=0
    print(b)
    while i<=len(a)-1:
        if a[i]!=0:
           print(i, j,'ok')
           b[j]=a[i]
           print(i,j)
           i=i+1
           j=j-1
        else:
            b[k]=a[i]
            k=k+1
            i=i+1
    print(b)

- Harsh October 04, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

a=[3,2,0,3,1,3,0,0,1,0]
b=[None]*len(a)
def movezeroo(a):
i=0
j=len(a)-1
k=0
print(b)
while i<=len(a)-1:
if a[i]!=0:
print(i, j,'ok')
b[j]=a[i]
print(i,j)
i=i+1
j=j-1
else:
b[k]=a[i]
k=k+1
i=i+1
print(b)

- Anonymous October 04, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

import java.util.Arrays;
	
public class MoveNonZeroElementsToEndOfArray {
	public static void main(String[] args){
		int test1[] = new int[] {1,0,-2,0,3};
		int test2[] = new int[] {0,0};
		int test3[] = new int[] {1,2,3};
		
		System.out.println(Arrays.toString(test1));
		compactify(test1);
		System.out.println(Arrays.toString(test1));
		
		System.out.println(Arrays.toString(test2));
		compactify(test2);
		System.out.println(Arrays.toString(test2));
		
		System.out.println(Arrays.toString(test3));
		compactify(test3);
		System.out.println(Arrays.toString(test3));
   }
   
   public static int compactify(int[] inp) {
	   int n = inp.length;
	   int destIndex = -1;
	   for (int i = n-1; i >= 0; i--) {
		   if ((destIndex > 0) && (inp[i] != 0)){
			   // swap inp[i] and inp[destIndex]
			   int tmp = inp[i];
			   inp[i] = inp[destIndex];
			   inp[destIndex] = tmp;
			   destIndex--;
		   } else if ((destIndex < 0) && (inp[i] == 0)) {
			   destIndex = i;
		   }
	   }
	   System.out.println("#non zero " + (n-(destIndex+1)));
	   return destIndex+1;
   }
}

- just_do_it November 11, 2018 | Flag Reply


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