check-if-n-and-its-double-exist

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1346. Check If N and Its Double Exist (Easy)

Given an array arr of integers, check if there exists two integers N and M such that N is the double of M ( i.e. N = 2 * M).

More formally check if there exists two indices i and j such that :

• i != j
• 0 <= i, j < arr.length
• arr[i] == 2 * arr[j]

 

Example 1:

Input: arr = [10,2,5,3]
Output: true
Explanation: N = 10 is the double of M = 5,that is, 10 = 2 * 5.

Example 2:

Input: arr = [7,1,14,11]
Output: true
Explanation: N = 14 is the double of M = 7,that is, 14 = 2 * 7.

Example 3:

Input: arr = [3,1,7,11]
Output: false
Explanation: In this case does not exist N and M, such that N = 2 * M.

 

Constraints:

• 2 <= arr.length <= 500
• -10^3 <= arr[i] <= 10^3

Related Topics

[Array] [Hash Table] [Two Pointers] [Binary Search] [Sorting]

Similar Questions

1. Keep Multiplying Found Values by Two (Easy)

Hints

Hint 1

Loop from i = 0 to arr.length, maintaining in a hashTable the array elements from [0, i - 1].

Hint 2

On each step of the loop check if we have seen the element 2 * arr[i] so far or arr[i] / 2 was seen if arr[i] % 2 == 0.