## Facebook Interview Question for Software Engineers

Country: United States
Interview Type: In-Person

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

``````public void sampleIdx(int[] array){
if(array == null || array.length == 0){
return;
}
Random rnd = new Random();
int res = 0, max = Integer.MIN_VALUE, count = 0;
for(int i = 0; i < array.length; i++){
if(max < array[i]){
max = array[i];
res = i;
count = 1;
}else if(max == array[i]){
count++;
int idx = rnd.nextInt(count); //(0, k - 1)
if(idx == 0){

res = i;
System.out.print(“A max value index up to the ”+i +”th element is ” + res;
);

}
}
}
}``````

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0
of 0 vote

public void test() {
int[] items = { 11, 30, 2, 30, 30, 30, 6, 2, 62, 62 };

List<Integer> maxIndexes = new ArrayList<Integer>();
int max = 0;
for (int i = 0; i < items.length; i++) {
int maxIndex = 0;
if (items[i] > max) {
maxIndexes.clear();
max = items[i];
} else if (items[i] == max) {
}
System.out.println(maxIndexes.get(new Random().nextInt(maxIndexes
.size())));
}

}

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0
of 0 vote

Python solution

``````def get_max(l = [11,30,2,30,30,30,6,2,62]):
rand = random.randint(0, len(l))
max_integer = (max(l[:rand]))
indexes=[]
for i in range(rand):
if l[i] == max_integer:
indexes.append(i)
print(rand)
print(max_integer)
print(indexes)``````

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0
of 0 vote

``````/*
In the current form, the question is ill posed.
It is as good as asking, given an array, find which indices
the maximal elements are - and return one at random.
More realistic and proper question would be:

Given a stream of integers, at any given time, if we were to ask
Give me a random index where the maximal element has appeared.

That would be worth interesting effort.
So we start.
*/
def bucket : { val : num('-inf'), indices : list(-1), cur_index : -1  }

def find_random_index( integer_iterator , bucket ){
if ( integer_iterator.hasNext ){
bucket.cur_index += 1
next_int = integer_iterator.next()
if ( next_int > bucket.val ){
bucket.val = next_int
bucket.indices = list( bucket.cur_index )
} else if ( next_int == bucket.val ){
bucket.indices +=  bucket.cur_index
}
}
random( bucket.indices ) // return a random value from collection
}``````

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0
of 0 vote

``````return list.slice(0, cut + 1).reduce((accumulator, current, index, array) => {
return (current >= array[accumulator]) ? index : accumulator;
}, 0);``````

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0
of 0 vote

Javascript solution

``````const findRadomMatchingIndex = arr => {
const matchesMap = {};
let max = Number.MIN_VALUE;
arr.forEach((el, idx) => {
if (el > max) {
max = el;
}
matchesMap[el] ? matchesMap[el].push(idx) : matchesMap[el] = [idx];
});
return matchesMap[max][Math.floor(Math.random() * matchesMap[max].length)]
}``````

Comment hidden because of low score. Click to expand.
0
of 0 vote

Here is my proposal in Python:

``````from random import randint

def parseArray(a = [11, 30, 2, 30, 30, 30, 6, 2, 62, 62]):
max_value = 0
for i in range(len(a)):
if a[i] > max_value:
max_value = a[i]
max_indexes = []
if a[i] == max_value:
max_indexes.append(i)
print('Seen so far: {}'.format(a[:i+1]))
print('Max: {}'.format(max_value))
print('Max indexes: {}'.format(max_indexes))
print('Random max index: {}'.format(
max_indexes[randint(0, len(max_indexes) - 1)]))
print('')``````

Comment hidden because of low score. Click to expand.
0
of 0 vote

Here is my proposal in Python:

``````from random import randint

def parseArray(a = [11, 30, 2, 30, 30, 30, 6, 2, 62, 62]):
max_value = 0
for i in range(len(a)):
if a[i] > max_value:
max_value = a[i]
max_indexes = []
if a[i] == max_value:
max_indexes.append(i)
print('Seen so far: {}'.format(a[:i+1]))
print('Max: {}'.format(max_value))
print('Max indexes: {}'.format(max_indexes))
print('Random max index: {}'.format(
max_indexes[randint(0, len(max_indexes) - 1)]))
print('')``````

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0
of 0 vote

``````#include <vector>
#include <map>
#include <stdlib.h>     /* srand, rand */
#include <time.h>       /* time */
#include "utils.h"
class Solution {
public:
int getMaxValueIndex(std::vector<int> v, int n) {
std::map<int,std::vector<int>> positions;
for (int i = 0; i <= n; ++i) {
positions[v[i]].push_back(i);
}
const auto it = positions.rbegin();
if(it != positions.rend()) {
//std::cout << it->first << " " << it->second << std::endl;
srand (time(NULL));
return it->second[rand() % it->second.size()];
}
return -1;
}
};

// Driver code
// ===========================================

int main()
{
Solution sol;
std::vector<int> input = {11,30,2,30,30,30,6,2,62,62};
int output = sol.getMaxValueIndex(input,5);
std::cout << output << std::endl;

return 0;
}``````

Comment hidden because of low score. Click to expand.
0
of 0 vote

Here is the pseudo code for this -

``````max = INT_MAX
maxMap = new Map
holder = list
foreach i in A upto I
if(A[i] >= max)
then
max = A[i]
if(maxMap.containsKey(max)
then
holder = maxMap.get(max)
else
holder = new list

maxMap.put(max, holder)
end

maxEntry = map.entrySet().max(e -> e.value)
random = new random(maxEntry.value)
while random exhausted
print random.nextInt()

Time: O(I)
Space: O(n)``````

Comment hidden because of low score. Click to expand.
0
of 0 vote

Here is the pseudo code for this -

``````max = INT_MAX
maxMap = new Map
holder = list
foreach i in A upto I
if(A[i] >= max)
then
max = A[i]
if(maxMap.containsKey(max)
then
holder = maxMap.get(max)
else
holder = new list

maxMap.put(max, holder)
end

maxEntry = map.entrySet().max(e -> e.value)
random = new random(maxEntry.value)
while random exhausted
print random.nextInt()

Time: O(I)
Space: O(n)``````

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0
of 0 vote

``````// Given an array of numbers and position to stop, find the max value
// up to the stop. Then randomly return index of the max value.

function randomIndexOfMaxValue(data, pos) {
// Iterate to pos and find the max value
var indexes = []
var max = 0
for (var i = 0; i < Math.min(pos, data.length); i++) {
if (max < data[i]) {
max = data[i]
indexes = [i]
} else if (max == data[i]) {
indexes.push(i)
}
}

// randomly return index of max value
console.debug(indexes)
return indexes[Math.floor(Math.random() * indexes.length)]
}

console.log(randomIndexOfMaxValue([11, 30, 2, 30, 30, 30, 6, 2, 62, 62], 10))``````

Comment hidden because of low score. Click to expand.
0
of 0 vote

import random
def find_random_Maxindex(arr):
if not arr:
return -1
max_num = arr[0]
indices = [0]
for i in range(1,len(arr)):
if arr[i] > max_num:
max_num = arr[i]
indices = [i]
elif arr[i] == max_num:
indices.append(i)
else:
continue
return random.choice(indices)
print(find_random_Maxindex([11,30,2,30,30,30,6,2]))
print(find_random_Maxindex([]))

Comment hidden because of low score. Click to expand.
0
of 0 vote

"""
import random
def find_random_Maxindex(arr):
if not arr:
return -1
max_num = arr[0]
indices = [0]
for i in range(1,len(arr)):
if arr[i] > max_num:
max_num = arr[i]
indices = [i]
elif arr[i] == max_num:
indices.append(i)
else:
continue
return random.choice(indices)
print(find_random_Maxindex([11,30,2,30,30,30,6,2]))
print(find_random_Maxindex([]))
"""

Comment hidden because of low score. Click to expand.
0
of 0 vote

``````import random
def find_random_Maxindex(arr):
if not arr:
return -1
max_num = arr[0]
indices = [0]
for i in range(1,len(arr)):
if arr[i] > max_num:
max_num = arr[i]
indices = [i]
elif arr[i] == max_num:
indices.append(i)
else:
continue
return random.choice(indices)
print(find_random_Maxindex([11,30,2,30,30,30,6,2]))
print(find_random_Maxindex([]))``````

Comment hidden because of low score. Click to expand.
0
of 0 vote

``````import random
def find_random_Maxindex(arr):
if not arr:
return -1
max_num = arr[0]
indices = [0]
for i in range(1,len(arr)):
if arr[i] > max_num:
max_num = arr[i]
indices = [i]
elif arr[i] == max_num:
indices.append(i)
else:
continue
return random.choice(indices)
print(find_random_Maxindex([11,30,2,30,30,30,6,2]))
print(find_random_Maxindex([]))``````

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