## Facebook Interview Question

Software Engineers**Country:**United States

**Interview Type:**In-Person

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();

maxIndexes.add(i);

max = items[i];

} else if (items[i] == max) {

maxIndexes.add(i);

}

System.out.println(maxIndexes.get(new Random().nextInt(maxIndexes

.size())));

}

}

```
/*
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
}
```

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)]
}
```

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('')
```

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('')
```

```
#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;
}
```

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