Check If N and Its Double ExistLeetcode Problem 1346

英文原题

Given an array arr of integers, check if there exists two integers N and M such that N is the double of 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

中文翻译

给定一个整数数组，检查数组中是否存在两个数 N 和 M 使得 N 是 M 的两倍。

严格来讲，就是检查是否存在两个索引 i 和 j 使得：

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

样例 1

Input: arr = [10,2,5,3]
Output: true
解释: N = 10 是 M = 5 的两倍，也就是, 10 = 2 * 5.

样例 2

Input: arr = [7,1,14,11]
Output: true
解释: N = 14 是 M = 7 的两倍，也就是, 14 = 2 * 7.

样例 3

Input: arr = [3,1,7,11]
Output: false
解释: 这里不存在 N 和 M, 使得 N = 2 * M.

约束

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

问题签名

Java 代码

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class Solution {    public boolean checkIfExist(int[] arr) {     }}

Java Script 代码

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/*** @param {number[]} arr* @return {boolean}*/var checkIfExist = function(arr) { };

Python 代码

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class Solution:    def checkIfExist(self, arr: List[int]) -> bool:

Go 代码

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func checkIfExist(arr []int) bool { }

Swift 代码

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class Solution {    func checkIfExist(_ arr: [Int]) -> Bool {     }}