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1313-decompress-run-length-encoded-list.js
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1313-decompress-run-length-encoded-list.js
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// 1313. Decompress Run-Length Encoded List
// https://leetcode.com/problems/decompress-run-length-encoded-list/
/*
We are given a list nums of integers representing a list compressed with
run-length encoding.
Consider each adjacent pair of elements [a, b] = [nums[2*i], nums[2*i+1]] (with
i >= 0). For each such pair, there are a elements with value b in the
decompressed list.
Return the decompressed list.
*/
import { deepStrictEqual } from 'assert';
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
// Runtime: 76 ms, faster than 89.07% of JavaScript online submissions
// Memory Usage: 37.3 MB, less than 100.00% of JavaScript online submissions
// /**
// * @param {number[]} nums
// * @return {number[]}
// */
// const decompressRLElist = nums => {
// const inflated = [];
// for (let i = 0; i < nums.length - 1; i += 2)
// inflated.push(...new Array(nums[i]).fill(nums[i + 1]));
// return inflated;
// };
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
// Runtime: 84 ms, faster than 55.51% of JavaScript online submissions
// Memory Usage: 41.5 MB, less than 100.00% of JavaScript online submissions
/**
* @param {number[]} nums
* @return {number[]}
*/
const decompressRLElist = (deflated, inflated = []) =>
!deflated.length
? inflated
: decompressRLElist(
deflated.slice(2),
inflated.concat(new Array(deflated[0]).fill(deflated[1])),
);
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
// Example 1:
deepStrictEqual(decompressRLElist([1, 2, 3, 4]), [2, 4, 4, 4]);
// Explanation: The first pair [1,2] means we have freq = 1 and val = 2 so we
// generate the array [2]. The second pair [3,4] means we have freq = 3 and val
// = 4 so we generate [4,4,4]. At the end the concatenation [2] + [4,4,4] is
// [2,4,4,4].