Sorting algorithm--shell sorting

Principle

Divides the sorted array into sub-sequences (this depends on the originally set step value), then inserts the sequence directly between the individual sub-sequences, and then the increment (that is, the step value) and then inserts the sort, until the sequence is basically stable (the step size is small enough), a direct insert sort of the series, When sorting is good, the efficiency of direct insertion is quite high.

Analysis

In the worst case, each number will always be compared in the process of each comparison, so in the worst case its time complexity O(n2). In the best case, the sequence is basically ordered only once, so the time complexity is O(n). The space complexity is O(1).

C Language Implementation

Void swap (void *a, void *b, int size) {    void *tmp  = malloc (size);     memcpy (tmp, a, size);     memcpy (a, b, size);     memcpy (b, tmp, size);     Free (TMP);} Void shell_sort (Int *arr, int arrlen) {    int i = 0,  j = 0;    int gap = 0;    if (NULL  == arr | |  0 >= arrlen) {        return ;     }    for (gap = arrlen/2; gap>0; gap /= 2) {         for (I = gap; i < arrlen; ++i) {            for (j = i - gap;& nbSP;J&NBSP;&GT;=0;&NBSP;J&NBSP;-=&NBSP;GAP) {                 if (Arr[j] > arr[j + gap]) {                     swap (&arr[j],  &arr[j + gap], sizeof (Arr[j]);                 }             }        }    }}

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Sorting algorithm--shell sorting