Integer array merge [JS]

Problem description

Topic link - Cattle guest
Merge two arrays of integers in ascending order , And filter out duplicate array elements .
When outputting, there is no space between two adjacent numbers .

Input description ：

Enter description , Enter... In the following order ：

• Enter the number of the first array
• Enter the value of the first array
• Enter the number of the second array
• Enter the value of the second array

Output description ：

Output the merged array

Example 1

Input ：

3
1 2 5
4
-1 0 3 2

Output ：

-101235

Solved JS Code

let arr_num = 2;
let num;
let ans = [];
while (arr_num--) {
    
  num = readline();
  let temp = readline();
  temp = temp.split(" ");
  temp = Array.from(new Set(temp));
  temp = temp.sort();
  ans.push(temp);
}

function flat(input){
    
    const stack = [...input];
    const res = [];
    while(stack.length){
    
        const next = stack.pop();
        if(Array.isArray(next)){
    
            stack.push(...next);
        }else{
    
            res.push(next);
        }
    }
    return res.reverse();
}

ans = flat(ans);

ans = Array.from(new Set(ans));

ans.sort((a , b) => {
    
    return a - b; 
})

ans = ans.join("")
console.log(ans);

Code interpretation

The first time I saw this topic, I thought JS Array de duplication in Set, So choose to use js To write the title

First of all, the idea of this topic is actually very simple , After input , Ascending , duplicate removal , Then the output

Actually , At the beginning , I didn't even notice , At first glance, I was attracted by the array , I didn't notice Ascending also You need to enter four numbers , Then there are a few js Basic questions , Submitted a total of 6 Time ……

A few points to be noted

1.readline yes string

I passed readline Function reads the input characters , At first I took it for granted that this was an array , Errors are always reported when processing the results , Prototype chains cannot be used Array The method in

So using split(" ") Split string , Into an array

2. Can't use flat

After processing , Become a two-dimensional array , So it's like passing flat The method is flattened directly , But Niuke js The environment does not seem to support this method , So I wrote a flat Method

Actually flat The source code of is also quite simple

• adopt ... The extension operator deconstructs the input value
• while loop stack The length of
  • adopt pop Method to take out the elements at the top of the stack
  • Determine whether it is an array
    • yes —— continue push(...next)
    • no —— Then record res Array

After completion , Remember to pass reverse Function returns an array in the original order , Because it is traversed from back to front , So we need to reverse the order

function flat(input){
    
    const stack = [...input];
    const res = [];
    while(stack.length){
    
        const next = stack.pop();
        if(Array.isArray(next)){
    
            stack.push(...next);
        }else{
    
            res.push(next);
        }
    }
    return res.reverse();
}

3. Array weight removal

Directly through Array.from(new Set( Array )) You can complete , To borrow Set The data structure of is completed

4.sort The sorting method of functions

sort The of the function is through ASCII Code to sort , So this happens
The original array is 2,3,6,8,11
It turns out to be
11 2 3 6 8

because 1 Of ASCII Smaller size , So it was put in the first place , So we need to rewrite

ans.sort((a , b) => {
    
    return a - b; 
})

If descending order is required , take a,b The other way around

5. Array to string ——join

The final question result needs to be output Without spaces The output format of , So you need to convert the array into a string

Directly through join Function conversion is enough

ans = ans.join("")