Problems with js array operation

given an ordered and non-repeating array arr1 = [a _ 1Magi a2recover.dagan], a subset of the array arr2 = [b _ 1rect b _ 2jn] (the order is the same as arr1)
any element ai of a given arr1, please insert it into arr2 and make sure that the order is the same as the order of arr1

.

for example, arr1, arr2, and arr2 now want to insert 4 into arr2
, and the result is

.

find an elegant algorithm

-split line-

I adopted @ hkuclion"s answer and made a small modification 

let source = [3,5,4,8];
let target = [5,8];
let needle = 4;

let source_index = source.indexOf(needle);
if(source_index !== -1){
    let target_index = -1;
    while (source_index && target_index === -1) {
        target_index = target.indexOf(source[--source_index]);
    }
    target.splice(target_index + 1, 0, needle);
}
Javascript
Mar.10,2021

or modify the way of comparison in dichotomy 

let arr1 = [3,5,4,8] 
let arr2 = [5,8] 
let indexMap = {}
for(let i=0;i<arr1.length;iPP){
    indexMap[arr1[i]] = i
}
insert(arr2,0,arr2.length,4)
console.log(JSON.stringify(arr2))

function insert(arr,l,r,num){
    if(l==r){
        arr.splice(l, 0, num)
        return
    }
    let index = parseInt((r+l)/2)
    if(indexMap[arr[index]]<indexMap[num]){
        insert(arr,index+1,r,num)
    }else{
        insert(arr,l,index,num)
    }
}

try the following code 

let source = [3,5,4,8];
let target = [5,8];
let needle = 4;

let source_index = source.indexOf(needle);
if(source_index !== -1){
    let target_index = source_index? target.indexOf(source[source_index - 1]) + 1:source_index;
    target.splice(target_index, 0, needle);
}
 

 since it is orderly. In fact, it doesn't matter whether there is  arr1 . 


 in order, you just use dichotomy to put  ai  into  arr2 .

Previous: On the problem of data assignment

Next: Hadoop cluster master server has namenode, two slave servers have DataNode, is that right?

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1ead878-2160.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1ead878-2160.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?