问题
for (int i = 1; i < data.Count; i++)
{
int j = i;
while (j > 0)
{
if (numarray[j - 1] > numarray[j])
{
int temp = numarray[j - 1];
numarray[j - 1] = numarray[j];
numarray[j] = temp;
j--;
}
else
break;
}
}
Can someone help me identify what is the sorting algorithm of the above code? I know that bubble sort is not very efficient. If I am to use insertion sort algorithm instead, how can I improve the above code. Thankyou!
回答1:
Just do this:
Array.Sort(data);
回答2:
the most efficient way should be Array.Sort(data); which uses quicksort
some other sorting algorithms:
BubbleSort
public static void BubbleSort<T>(this List<T> source) where T : IComparable<T>
{
IComparer<T> comparer = Comparer<T>.Default;
for (int i = (source.Count - 1); i >= 0; i--)
{
for (int j = 1; j <= i; j++)
{
if (comparer.Compare(source[j - 1], source[j]) > 0)
{
var temp = source[j - 1];
source[j - 1] = source[j];
source[j] = temp;
}
}
}
}
InsertionSort
public static void InsertionSort<T>(this List<T> source) where T : IComparable<T>
{
IComparer<T> comparer = Comparer<T>.Default;
int j;
for (int i = 1; i < source.Count; i++)
{
var index = source[i];
j = i;
while ((j > 0) && comparer.Compare(source[j - 1], index) > 0)
{
source[j] = source[j - 1];
j = j - 1;
}
source[j] = index;
}
}
HeapSort
public static void HeapSort<T>(this List<T> source) where T : IComparable<T>
{
int heapSize = source.Count;
for (int p = (heapSize - 1) / 2; p >= 0; p--)
{
HeapSort_sub(source, heapSize, p);
}
for (int i = source.Count - 1; i > 0; i--)
{
var temp = source[i];
source[i] = source[0];
source[0] = temp;
heapSize--;
HeapSort_sub(source, heapSize, 0);
}
}
private static void HeapSort_sub<T>(List<T> source, int heapSize, int index)
{
IComparer<T> comparer = Comparer<T>.Default;
int left = (index + 1) * 2 - 1;
int right = (index + 1) * 2;
int largest = 0;
if (left < heapSize && comparer.Compare(source[left], source[index]) > 0)
{
largest = left;
}
else
{
largest = index;
}
if (right < heapSize && comparer.Compare(source[right], source[largest]) > 0)
{
largest = right;
}
if (largest != index)
{
var temp = source[index];
source[index] = source[largest];
source[largest] = temp;
HeapSort_sub(source, heapSize, largest);
}
}
QuickSort
public static void QuickSort<T>(this List<T> source) where T : IComparable<T>
{
QuickSort_sub(source, 0, source.Count - 1);
}
private static void QuickSort_sub<T>(List<T> source, int left, int right)
{
IComparer<T> comparer = Comparer<T>.Default;
int i = left, j = right;
var pivot = source[(left + right) / 2];
while (i <= j)
{
while (comparer.Compare(source[i], pivot) < 0)
{
i++;
}
while (comparer.Compare(source[j], pivot) > 0)
{
j--;
}
if (i <= j)
{
var tmp = source[i];
source[i] = source[j];
source[j] = tmp;
i++;
j--;
}
}
if (left < j)
{
QuickSort_sub(source, left, j);
}
if (i < right)
{
QuickSort_sub(source, i, right);
}
}
StoogeSort
public static void StoogeSort<T>(this List<T> L) where T : IComparable
{
StoogeSortSub(L, 0, L.Count - 1);
}
private static void StoogeSortSub<T>(List<T> L, int i, int j) where T : IComparable
{
if (L[j].CompareTo(L[i]) < 0)
{
T tmp = L[i];
L[i] = L[j];
L[j] = tmp;
}
if (j - i > 1)
{
int t = (j - i + 1) / 3;
StoogeSortSub(L, i, j - t);
StoogeSortSub(L, i + t, j);
StoogeSortSub(L, i, j - t);
}
}
SelectionSort
public static void SelectionSort<T>(this List<T> source) where T : IComparable<T>
{
IComparer<T> comparer = Comparer<T>.Default;
int min;
for (int i = 0; i < source.Count - 1; i++)
{
min = i;
for (int j = i + 1; j < source.Count; j++)
{
if (comparer.Compare(source[j], source[min]) < 0)
{
min = j;
}
}
var temp = source[i];
source[i] = source[min];
source[min] = temp;
}
}
CocktailSort
public static void CocktailSort<T>(this List<T> A) where T : IComparable<T>
{
IComparer<T> comparer = Comparer<T>.Default;
bool swapped;
do
{
swapped = false;
for (int i = 0; i <= A.Count - 2; i++)
{
if (comparer.Compare(A[i] , A[i + 1])> -1)
{
T temp = A[i];
A[i] = A[i + 1];
A[i + 1] = temp;
swapped = true;
}
}
if (!swapped)
{
break;
}
swapped = false;
for (int i = A.Count - 2; i >= 0; i--)
{
if (comparer.Compare(A[i], A[i + 1]) > -1)
{
T temp = A[i];
A[i] = A[i + 1];
A[i + 1] = temp;
swapped = true;
}
}
} while (swapped);
}
GnomeSort
public static void GnomeSort<T>(this List<T> a) where T : IComparable<T>
{
IComparer<T> comparer = Comparer<T>.Default;
int i = 1, j = 2;
while (i < a.Count)
{
if (comparer.Compare(a[i - 1] ,a[i])<1)
{
i = j;
j++;
}
else
{
T tmp = a[i - 1];
a[i - 1] = a[i];
a[i] = tmp;
i -= 1;
if (i == 0)
{
i = 1;
j = 2;
}
}
}
}
ShellSort
public static void ShellSort<T>(this List<T> source) where T : IComparable<T>
{
IComparer<T> comparer = Comparer<T>.Default;
int j, increment;
increment = 3;
while (increment > 0)
{
for (int i = 0; i < source.Count; i++)
{
j = i;
var temp = source[i];
while ((j >= increment) && comparer.Compare(source[j - increment], temp) > 0)
{
source[j] = source[j - increment];
j = j - increment;
}
source[j] = temp;
}
if (increment / 2 != 0)
{
increment = increment / 2;
}
else if (increment == 1)
{
increment = 0;
}
else
{
increment = 1;
}
}
}
回答3:
.NET has a default sort solution for arrays. Array.Sort. By default, .NET implements a Quicksort algorithm which sorts between O(n) and O(n log n). (this is much faster than a bubble sort).
You can use it by doing Array.Sort(your_array), or if you need something more complicated (like sorting objects, or sorting in reverse), there is an overload which takes in an IComparer object.
来源：https://stackoverflow.com/questions/35653986/i-want-an-efficient-sorting-algorithm-to-sort-an-array