Kata

This is the Performance version of coding 3min series. If your code runs more than 6000ms, please optimize your code or try the simple version

Task:

This time, we coding halfIt with an array.

Give you a number array arr, return "Half" of arr.

What does "Half" mean? In this kata, "Half" means:

remove some element from arr, left half of the sum value of the array

The array is not sorted, all of the element is positive integer.

We need to find a balance point in the array, the array is divided into two parts from this point. try to make the two parts equal or the difference is the smallest, we always leave fewer elements and remove more elements, if the number of elements on both sides are same, leave the left part and remove the right part.

Some example to help you understand the rules:

arr=[1,1,1,1,1,1,1,1] -->  [1,1,1,1,  |   1,1,1,1]
                         keep          remove
halfIt([1,1,1,1,1,1,1,1])=[1,1,1,1]

arr=[1,1,1,1,2,2,2,2] -->  [1,1,1,1,2,  |  2,2,2]
                             remove         keep
halfIt([1,1,1,1,2,2,2,2])=[2,2,2]

arr=[1,2,3,4,4,3,2,1] -->  [1,2,3,4,  |  4,3,2,1]
                             keep         remove    
halfIt([1,2,3,4,4,3,2,1])=[1,2,3,4]

arr=[1,2,3,4,5,6,7,8] -->  [1,2,3,4,5,6,  |  7,8]
sum of arr=36               1+2+3+4+5+6=21   7+8=15
                               remove        keep
halfIt([1,2,3,4,5,6,7,8])=[7,8]

arr=[10,8,5,4,7,6,2] -->  [10,8,5,  |  4,7,6,2]
sum of arr=36              10+8+5=23   4+7+6+2=19
                            keep        remove    
halfIt([10,8,5,4,7,6,2])=[10,8,5]

some corner case:

If elements in arr less than 2, should return the original array
halfIt([1])=[1]
halfIt([])=[]

If arr is not an array, return null
halfIt("?")=null
halfIt(1)=null
halfIt(true)=null
halfIt({})=null
halfIt(null)=null
halfIt(undefined)=null


  

Series:

• Count animals
• A*B=C
• Half it III
• Half it IV