Leetcode 1313. Decompress Run-Length Encoded List

題目

Input: nums = [1,2,3,4]
Output: [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].

解法思維

var decompressRLElist = function(nums) {
    let arr = [];
    function pushTo(count, num) {
        if (count === 0) return;
            arr.push(num);
            pushTo(count-1, num);
    }
    for (let i = 0; i < nums.length; i += 2) {
      pushTo(nums[i], nums[i+1]);
    }
    return arr;
};

var decompressRLElist = function(nums) {
    let result = []
    
    for(let i=0; i<nums.length; i+=2) {
        const frequency = nums[i]
        const value = nums[i+1]
        
        // result = [...result, ...new Array(frequency).fill(value)]
        result.push(...new Array(frequency).fill(value))
    }
    
    return result
};