Leetcode - Check If N and Its Double Exist
https://leetcode.com/problems/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]
Time complexity: O(n)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | func checkIfExist(arr []int) bool { hash := map[int]bool{} count0 := 0 for i := 0; i < len(arr); i++ { if arr[i] == 0 { count0++ } hash[arr[i]*2] = true } if count0 > 1 { return true } for i := 0; i < len(arr); i++ { if hash[arr[i]] && arr[i] != 0 { return true } } return false} |
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