常见的排序算法

归并排序

var sortArray = function (nums) {
  return mergesort(nums, 0, nums.length - 1);
};
function mergesort(nums, left, right) {
  if (left >= right) return nums;
  let mid = (left + right) >> 1;
  mergesort(nums, left, mid);
  mergesort(nums, mid + 1, right);
  return merge(nums, left, mid, right);
}
function merge(nums, left, mid, right) {
  let ans = [];
  let cur = 0,
    i = left,
    j = mid + 1;
  while (i <= mid && j <= right) {
    if (nums[i] < nums[j]) {
      ans[cur++] = nums[i++];
    } else {
      ans[cur++] = nums[j++];
    }
  }
  while (i <= mid) {
    ans[cur++] = nums[i++];
  }
  while (j <= mid) {
    ans[cur++] = nums[j++];
  }
  for (let i = 0; i < ans.length; i++) {
    nums[i + left] = ans[i];
  }
  return nums;
}