golang leetcode 30天挑戰 11th day -decompressRLElist

題目解讀：

題目來源:

decompress-run-length-encoded-list

原文:

We are given a list nums of integers representing a list compressed with run-length encoding.

Consider each adjacent pair of elements [freq, val] = [nums[2i], nums[2i+1]] (with i >= 0). For each such pair, there are freq elements with value val concatenated in a sublist. Concatenate all the sublists from left to right to generate the decompressed list.

Return the decompressed list.

解讀：

給定一個正整數陣列nums 長度是2的倍數

其中 對於每2個 元素個別代表 出現的頻率 跟 數值

[freq val] = [nums[2 * i] nums[2 * i+1]] 其中 i > 0

舉例來說：

[1 2 3 4] => 1 [1 2] => [2] 值為2 出現次數1
2 [3 4] => [4 4 4] 值為4 出現次數3
所以最後結果為 [2 4 4 4]
求給定的nums 的 還原陣列

初步解法:

初步觀察:

對於每個nums
其中需要每次讀取兩個元素來做處理

然後每次需要產生新的array

最後再join成新的陣列

初步設計:

given an integer array nums

step 0: let an integer array result = []

step 1: let an integer length = length of nums /2, a integer idx = 0

step 2: if idx > length go to step 6

step 3: let value = nums[2 * idx + 1], create a integer array extract with length of nums[2 * idx]

step 4: loop array extract for index = 0 to index < length of extract set extract[index] = value

step 5: result = append(result, extract...)

step 6: return result

my solution source code

decompressRLElist.go

package decompress_list

func decompressRLElist(nums []int) []int {
	result := []int{}
	length := len(nums) / 2
	for idx := 0; idx < length; idx++ {
		val := nums[2*idx+1]
		extract := make([]int, nums[2*idx])
		for i := range extract {
			extract[i] = val
		}
		result = append(result, extract...)
	}
	return result
}

遇到的困難

題目上理解的問題

因為英文不是筆者母語

所以在題意解讀上 容易被英文用詞解讀給搞模糊

pseudo code撰寫

一開始不習慣把pseudo code寫下來

因此 不太容易把自己的code做解析

golang table driven test不熟

對於table driven test還不太熟析

所以對於寫test還是耗費不少時間

測資的撰寫

package decompress_list

import (
	"reflect"
	"testing"
)

func Test_decompressRLElist(t *testing.T) {
	type args struct {
		nums []int
	}
	tests := []struct {
		name string
		args args
		want []int
	}{
		{
			name: "Example1",
			args: args{
				nums: []int{1, 2, 3, 4},
			},
			want: []int{2, 4, 4, 4},
		},
		{
			name: "Example2",
			args: args{
				nums: []int{1, 1, 2, 3},
			},
			want: []int{1, 3, 3},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := decompressRLElist(tt.args.nums); !reflect.DeepEqual(got, tt.want) {
				t.Errorf("decompressRLElist() = %v, want %v", got, tt.want)
			}
		})
	}
}

參考文章

golang test

結語

玉米想追求時髦，去燙頭了
結果怎麼樣了呢？

ANS: 爆米花