1let arr1 = [10]
2let arr2 = [2, 3]
3
4let arr3 = [1, 5, 9, 10, 15, 20]
5let arr4 = [2, 3, 8, 13]
6
7
8function mergeNoSpace(arr1, arr2) {
9    let m = arr1.length
10    let n = arr2.length
11    for(let i = n - 1; i >= 0; i--){
12        let last = arr1[m - 1];
13        let j;
14        for(j=m - 2; j>=0 && arr1[j] > arr2[i]; j--){
15            arr1[j+1] = arr1[j];
16            
17        }
18        if (last > arr2[i]){
19            arr1[j+1] = arr2[i]
20            arr2[i] = last
21        }
22    }
23    return [...arr1, ...arr2]
24}
25
26console.log(mergeNoSpace(arr1,arr2))
27console.log(mergeNoSpace(arr3,arr4))