function sort(arr){
if(arr.length < 2){
return arr;
}
let length = arr.length;
let halfNumber = Math.floor(length / 2);
let left = arr.slice(0, halfNumber);
let right = arr.slice(halfNumber);
return merge(sort(left), sort(right))
}
function merge(left, right){
let result = [];
let i = 0;
let j = 0;
while(left[i] !== undefined || right[j] !== undefined){
if(right[j] == undefined || right[j] > left[i]){
result.push(left[i]);
i++;
} else {
result.push(right[j]);
j++;
}
}
return result;
}
sort([2,6, 78, 86,34,56, 15, 90, 9, 25, 0, 64])
/*
[4,1,3,2] --> [4, 1] [3, 2] --> [4] [1] [3] [2]
sort([4,1,3,2]) --> merge(sort([4, 1]), sort([3, 2])) --> merge(merge(sort([4]), sort([1])),merge(sort([3]), sort([2])))
merge(merge([4], [1]), merge([3], [2])) --> merge([1, 4], [2, 3]) --> [1, 2, 3, 4]
*/
