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 != j0 <= i, j < arr.lengtharr[i] == 2 * arr[j]给一个数组，求是否存在两个数n和m是的n=2*m
一个hashtable解决了吧
class Solution(object): def checkIfExist(self, arr): """ :type arr: List[int] :rtype: bool """ d = {} for value in arr: if value * 2 in d: return True elif value % 2 == 0 and value // 2 in d: return True d[value] = 1 return False
1346. Check If N and Its Double Exist
原文：https://www.cnblogs.com/whatyouthink/p/13302209.html