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Unique Digit Products

Description

Let’s call product(x) the product of x’s digits. Given an array of integers a, calculate product(x) for each x in a, and return the number of distinct results you get.

Example

For a = [2, 8, 121, 42, 222, 23], the output should be uniqueDigitProducts(a) = 3.

Here are the products of the array’s elements:

  • 2: product(2) = 2;
  • 8: product(8) = 8;
  • 121: product(121) = 1 \* 2 \* 1 = 2;
  • 42: product(42) = 4 \* 2 = 8;
  • 222: product(222) = 2 \* 2 \* 2 = 8;
  • 23: product(23) = 2 \* 3 = 6.

As you can see, there are only 3 different products: 2, 6 and 8.

Input/Output

  • [execution time limit] 4 seconds (js)

  • [input] array.integer a

    Guaranteed constraints:
    1 ≤ a.length ≤ 105,
    1 ≤ a[i] ≤ 109.

  • [output] integer

    • The number of different digit products in a.

[JavaScript (ES6)] Syntax Tips

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// Prints help message to the console
// Returns a string
function helloWorld(name) {
console.log("This prints to the console when you Run Tests");
return "Hello, " + name;
}

Solution

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function uniqueDigitProducts(a) {
  return a
    .map((el) =>
      String(el)
        .split("")
        .map(Number)
        .reduce((b, c) => b * c, 1)
    )
    .filter((el, id, arr) => id === arr.indexOf(el)).length;
}