LeetCode JS30-Day29 | 2695. Array Wrapper 包裝陣列 Easy

Description❓

Create a class ArrayWrapper that accepts an array of integers in its constructor. This class should have two features:

• When two instances of this class are added together with the + operator, the resulting value is the sum of all the elements in both arrays.
• When the String() function is called on the instance, it will return a comma separated string surrounded by brackets. For example, [1,2,3].

建立一個類別ArrayWrapper，在其建構函式中接受整數陣列。 這個類別應該有兩個特點：

• 當使用+運算子將此類別的兩個實例相加時，結果值是兩個陣列中所有元素的總和。
• 當在實例上呼叫 String() 函數時，將傳回一個用括號括起來的逗號分隔字串。 例如，[1,2,3]。

Points

• 30Days of JS 工具書－陣列 Array
• 30Days of JS 工具書－Array.reduce() 左至右歸約
• 30Days of JS 工具書－Array.flat()多維陣列轉一維陣列

Solution✍️

[ ▶️挑戰這一題 ][ 本日代碼 ]

class ArrayWrapper {
    constructor(nums) {
      this.nums = nums;
    }
    //使用Array.flat(1); 將多維陣列平坦化為一維陣列
    //使用Array.reduce(); 相加所有元素
    valueOf() {
        const flattenArray = this.nums.flat(1);
        return flattenArray.reduce((sum, num) => sum + num, 0);
    }
    //使用Array.join(,) 把所有的元素中間用,隔開並組合成字串 
    toString() {
      return `[${this.nums.join(',')}]`;
    }
}

Testcase

let nums1 = [[1,2],[3,4]]
let ex1 = new ArrayWrapper(nums1);
console.log(ex1.valueOf()); // 10

let nums2 = [[23,98,42,70]]
let ex2 = new ArrayWrapper(nums2);
console.log(ex2.toString()); //[23,98,42,70]

let nums3 = [[],[]]
let ex3 = new ArrayWrapper(nums3);
console.log(ex3.valueOf()); // 0