>When no more interesting kata can be resolved, I just choose to create the new kata, to solve their own, to enjoy the process  --myjinxin2015 said
# Description:
 Give you two arrays `arr1` and `arr2`. They have the same length(length>=2). The elements of two arrays always be integer.
 Sort `arr1` according to the ascending order of arr2; Sort `arr2` according to the ascending order of arr1. Description is not easy to understand, for example:
 ```
 arr1=[5,4,3,2,1], 
 arr2=[6,5,7,8,9]
 ```
 Let us try to sorting arr1. 
 First, we need know the ascending order of arr2:
 ```
 [5,6,7,8,9]
 ```
 We can see, after sort arr2 to ascending order, some elements' index are changed:
 ```
 unsort arr2      ascending order arr2
 [6,5,7,8,9]--->      [5,6,7,8,9]
 index0(6)  --->      index1
 index1(5)  --->      index0
 index2(7)            index2(no change)
 index3(8)            index3(no change)
 index4(9)            index4(no change)
 ```
 So, wo need according to these changes to sorting arr1:
 ```
 unsort arr1          sorted arr1
 [5,4,3,2,1]--->      [4,5,3,2,1]
 index0(5)  --->      index1
 index1(4)  --->      index0
 index2(3)            index2(no change)
 index3(2)            index3(no change)
 index4(1)            index4(no change)
 So: sorted arr1= [4,5,3,2,1]
 ```
 And then, we sorting arr2 with the same process:
 ```
 unsort arr1      ascending order arr1
 [5,4,3,2,1]--->      [1,2,3,4,5]
 index0(5)  --->      index4
 index1(4)  --->      index3
 index2(3)            index2(no change)
 index3(2)  --->      index1
 index4(1)  --->      index0
 unsort arr2          sorted arr2
 [6,5,7,8,9]--->      [9,8,7,5,6]
 index0(6)  --->      index4
 index1(5)  --->      index3
 index2(7)            index2(no change)
 index3(8)  --->      index1
 index4(9)  --->      index0
 So: sorted arr2= [9,8,7,5,6]
 ```
 Finally, returns the sorted arrays by a 2D array: `[sorted arr1, sorted arr2]`
 Note: In ascending order sorting process(not the final sort), if some elements have same value, sort them according to their index; You can modify the original array, but I advise you not to do that. ;-)
```if:haskell
 Note: In Haskell, you are expected to return a tuple of arrays, and good luck trying to modifiy the original array. :]
```
# Some Examples and explain
```
sortArrays([5,4,3,2,1],[6,5,7,8,9]) should return
[[4,5,3,2,1],[9,8,7,5,6]]
sortArrays([2,1,3,4,5],[5,6,7,8,9]) should return
[[2,1,3,4,5],[6,5,7,8,9]]
sortArrays([5,6,9,2,6,5],[3,6,7,4,8,1]) should return
[[5,5,2,6,9,6],[4,3,1,6,8,7]]
```
import numpy as np

def sort_two_arrays(arr1, arr2):
    idx2 = np.argsort(arr2, kind='mergesort')
    idx1 = np.argsort(arr1, kind='mergesort')
    return [[arr1[i] for i in idx2], [arr2[i] for i in idx1]]
import numpy as np

def sort_two_arrays(arr1, arr2):
    idx2 = np.argsort(arr2, kind='mergesort')
    idx1 = np.argsort(arr1, kind='mergesort')
    return [[arr1[i] for i in idx2], [arr2[i] for i in idx1]]