008 Check If N and Its Double Exist

Check If N and Its Double Exist

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

Solution

code

JavaScript

var checkIfExist = function(arr) {
    let returnNum = false;
    let j = 1;
    arr.forEach((element) => {
        for(let index = j; index<arr.length; index++){
            if(element*2 == arr[index] || element == arr[index]*2){
                returnNum = true;
            }
        } 
        j++;       
    });
    return returnNum;
};