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1346-check-if-n-and-its-double-exist.js
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1346-check-if-n-and-its-double-exist.js
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// 1346. 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]
*/
// 〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰
// Runtime: 44 ms, faster than 99.61% of JavaScript online submissions
// Memory Usage: 33.9 MB, less than 100.00% of JavaScript online submissions
// /**
// * @param {number[]} arr
// * @return {boolean}
// */
// const checkIfExist = arr =>
// arr.some((n, idx) => {
// const i2n = arr.indexOf(n * 2);
// return -1 < i2n && idx !== i2n;
// });
// 〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰
// Runtime: 80 ms, faster than 77.79% of JavaScript online submissions
// Memory Usage: 41.9 MB, less than 7.55% of JavaScript online submissions
// /**
// * @param {number[]} arr
// * @return {boolean}
// */
// const checkIfExist = arr =>
// !arr.length
// ? false
// : arr.slice(1).includes(arr[0] * 2) || arr.slice(1).includes(arr[0] / 2)
// ? true
// : checkIfExist(arr.slice(1));
// 〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰
// Runtime: 68 ms, faster than 99.26% of JavaScript online submissions
// Memory Usage: 40 MB, less than 48.03% of JavaScript online submissions
// /**
// * @param {number[]} arr
// * @return {boolean}
// */
// const checkIfExist = arr =>
// !arr.length
// ? false
// : (x => arr.some(n => n === x * 2 || n === x / 2))(arr.pop())
// ? true
// : checkIfExist(arr);
// 〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰
// Runtime: 84 ms, faster than 55.69% of JavaScript online submissions
// Memory Usage: 41.3 MB, less than 9.99% of JavaScript online submissions
// /**
// * @param {number[]} arr
// * @return {boolean}
// */
// const checkIfExist = (arr, haystack = new Set()) =>
// arr.length &&
// (n =>
// haystack.has(n / 2) ||
// haystack.has(n * 2) ||
// (haystack.add(n) && checkIfExist(arr, haystack)))(arr.pop());
// 〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰
// Runtime: 76 ms, faster than 92.03% of JavaScript online submissions
// Memory Usage: 40.1 MB, less than 48.03% of JavaScript online submissions
/**
* @param {number[]} arr
* @return {boolean}
*/
const checkIfExist = arr =>
arr.length &&
((x => arr.some(n => n === x * 2 || n === x / 2))(arr.pop()) ||
checkIfExist(arr));
// 〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰
// Runtime: 132 ms, faster than 7.00% of JavaScript online submissions
// Memory Usage: 40.1 MB, less than 55.64% of JavaScript online submissions
// /**
// * @param {number[]} arr
// * @return {boolean}
// */
// function checkIfExist(arr) {
// const set = new Set();
// while (arr.length) {
// const n = arr.pop();
// if (set.has(n / 2) || set.has(n * 2)) return true;
// set.add(n, n * 2);
// }
// return false;
// }
// 〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰
import { ok } from 'assert';
// Example 1:
ok(checkIfExist([10, 2, 5, 3]));
// Explanation: N = 10 is the double of M = 5,that is, 10 = 2 * 5.
// Example 2:
ok(checkIfExist([7, 1, 14, 11]));
// Explanation: N = 14 is the double of M = 7,that is, 14 = 2 * 7.
// Example 3:
ok(!checkIfExist([3, 1, 7, 11]));
// Explanation: In this case does not exist N and M, such that N = 2 * M.
// Test
ok(!checkIfExist([-2, 0, 10, -19, 4, 6, -8]));
ok(checkIfExist([-20, 8, -6, -14, 0, -19, 14, 4]));
ok(!checkIfExist([0]));
ok(checkIfExist([0, 0]));