一些重要的排序算法

void PigeonholeSort(BYTE *array, int length)
{
    int b[256] = {0};
    int i,k,j = 0;
    for(i=0; i<length; i++)
        b[array[i]]++;
    for(i=0; i<256; i++)
        for(k=0; k<b[i]; k++)
            array[j++] = i;
}




多一次遍历的计数排序，排序字节串的话速度约是鸽巢排序的一半

C/C++ code

void CountingSort(BYTE * array, int length) { int t; int i, z = 0 ; BYTE min,max; int * count; min = max = array[ 0 ]; for (i = 0 ; i < length; i ++ ) { if (array[i] < min) min = array[i]; else if (array[i] > max) max = array[i]; } count = ( int * )malloc((max - min + 1 ) * sizeof ( int )); for (i = 0 ; i < max - min + 1 ; i ++ ) count[i] = 0 ; for (i = 0 ; i < length; i ++ ) count[array[i] - min] ++ ; for (t = 0 ; t <= 255 ; t ++ ) for (i = 0 ; i < count[t - min]; i ++ ) array[z ++ ] = (BYTE)t; free(count); }

快速排序，快排最标准的递归实现，速度约是std::sort的一半

C/C++ code

void swap(BYTE * a,BYTE * b) { BYTE tmp; if ( a != b ) { tmp = * a; * a = * b; * b = tmp; } } int partition(BYTE * arr, int left, int right) { int i = left - 1 , j = right; BYTE v = arr[right]; while ( 1 ) { while (arr[ ++ i] < v); while (arr[ -- j] > v) if (j == 1 ) break ; if (i >= j) break ; swap( & arr[i], & arr[j]); } swap( & arr[i], & arr[right]); return i; } void quicksort(BYTE * arr, int left, int right) { if (left < right) { int i = partition(arr,left,right); quicksort(arr,left,i - 1 ); quicksort(arr,i + 1 ,right); } } void QuickSort(BYTE * array, int length) { quicksort(array, 0 ,length - 1 ); }

这是速度与std::sort相当的三路划分快排

C/C++ code

void swap(BYTE * a,BYTE * b) { BYTE tmp; if ( a != b ) { tmp = * a; * a = * b; * b = tmp; } } void quicksort(BYTE * arr, int left, int right) { if (left < right) { BYTE v = arr[right]; int i = left - 1 ,j = right,p = left - 1 ,q = right,k = 0 ; while ( 1 ) { while (arr[ ++ i] < v); while (arr[ -- j] > v) if (j == left) break ; if (i >= j) break ; swap( & arr[i], & arr[j]); if (arr[i] == v) { p ++ ; swap( & arr[p], & arr[i]); } if (arr[j] == v) { q -- ; swap( & arr[q], & arr[j]); } } swap( & arr[i], & arr[right]); j = i - 1 ; i ++ ; for (k = left; k <= p; k ++ ,j -- ) swap( & arr[k], & arr[j]); for (k = right - 1 ; k >= q; k -- ,i ++ ) swap( & arr[k], & arr[i]); quicksort(arr,left,j); quicksort(arr,i,right); } } void QuickSort(BYTE * array, int length) { quicksort(array, 0 ,length - 1 ); }

相当简单的梳排序，效率是std::sort的三分之一

C/C++ code

void CombSort(BYTE * arr, int size) { UINT gap = size, swapped = 1 , i = 0 ; BYTE swap = 0 ; while ((gap > 1 ) || swapped) { if (gap > 1 ) gap = gap / 1.3 ; swapped = 0 ; i = 0 ; while ((gap + i) < size) { if (arr[i] - arr[i + gap] > 0 ) { swap = arr[i]; arr[i] = arr[i + gap]; arr[i + gap] = swap; swapped = 1 ; } ++ i; } } }

LSD基数排序，与std::sort速度相当，但是需要一个与输入缓冲一样大的缓冲区

C/C++ code

#define R 256 #define digit(a, d) ( a >> 8*d ) static BYTE * aux; void radix_sort(BYTE * arr, int left, int right) { if (left < right) { int d = 0 ; for (d = 3 ; d >= 0 ; d -- ) { int i = 0 , j = 0 , count[R + 1 ]; for (j = 0 ; j < R; j ++ ) count[j] = 0 ; for (i = left; i <= right; i ++ ) count[digit(arr[i],d) + 1 ] ++ ; for (j = 1 ; j < R; j ++ ) count[j] += count[j - 1 ]; for (i = left; i <= right; i ++ ) aux[count[digit(arr[i],d)] ++ ] = arr[i]; for (i = left; i <= right; i ++ ) arr[i] = aux[i - 1 ]; } } } void RadixSort(BYTE * array, int length) { aux = (BYTE * )malloc(length); radix_sort(array, 0 ,length - 1 ); free(aux); }

归并排序，效率越是std::sort的六分之一，通常的实现是递归，但和快排不同，归并改循环极其容易

C/C++ code

void merge(BYTE * array, int low, int mid, int high) { int i, k; BYTE * temp = (BYTE * ) malloc(high - low + 1 ); int begin1 = low; int end1 = mid; int begin2 = mid + 1 ; int end2 = high; for (k = 0 ; begin1 <= end1 && begin2 <= end2; ++ k) if (array[begin1] < array[begin2]) temp[k] = array[begin1 ++ ]; else temp[k] = array[begin2 ++ ]; while (begin1 <= end1) temp[k ++ ] = array[begin1 ++ ]; while (begin2 <= end2) temp[k ++ ] = array[begin2 ++ ]; for (i = 0 ; i < (high - low + 1 ); i ++ ) array[low + i] = temp[i]; free(temp); } void merge_sort(BYTE * array, UINT first, UINT last) { UINT mid,i; for (mid = 1 ; mid <= last - first; mid += mid) for (i = first; i <= last - mid; i += mid + mid) merge(array,i,i + mid - 1 ,min(i + mid + mid - 1 ,last)); } void MergeSort(BYTE * array, UINT length) { merge_sort(array, 0 ,length - 1 ); }