不知名排序
#include <stdio.h>int main(){int a[18] = {11,5,53,10,26,3,89,32,9,10,1,24,35,56,43,23,788,43};int i,j,k,n;n = sizeof(a) / sizeof(int);printf("n = %d\n", n);for (i = 1; i < n; i++) {for (j = 0; j < n - 1; j++) {if (a[i] > a[j]) {k = a[i];a[i] = a[j];a[j] = k;}}}for (i = 0; i < n; i++)printf(" %d ", a[i]);}
冒泡
冒泡排序（英语：Bubble Sort）是一种简单的排序算法。它重复地走访过要排序的数列，一次比较两个元素，如果他们的顺序（如从大到小、首字母从A到Z）错误就把他们交换过来。
#include <stdio.h>int main(){int a[18] = {11,5,53,10,26,3,89,32,9,10,1,24,35,56,43,23,788,43};int i,j,k,n;n = sizeof(a) / sizeof(int);printf("n = %d\n", n);for (i = 0; i < n; i ++) {for (j = 0; j < n - i - 1; j ++) {if (a[j] > a[j + 1]) {k = a[j + 1];a[j + 1] = a[j];a[j] = k;}}}for (i = 0; i < n; i++)printf(" %d ", a[i]);
}
选择排序
选择排序（Selection sort）是一种简单直观的排序算法。它的工作原理如下。首先在未排序序列中找到最小（大）元素，存放到排序序列的起始位置，然后，再从剩余未排序元素中继续寻找最小（大）元素，然后放到已排序序列的末尾。以此类推，直到所有元素均排序完毕。
#include <stdio.h>int main(){int a[18] = {11,5,53,10,26,3,89,32,9,10,1,24,35,56,43,23,788,43};int i,j,k,n,tmp;n = sizeof(a) / sizeof(int);printf("n = %d\n", n);for (i = 0; i < n; i ++) {tmp = i;for (j = i + 1; j < n; j++) {if(a[tmp] > a[j]) {tmp = j;}}if (tmp != i) {k = a[tmp];a[tmp] = a[i];a[i] = k;}}for (i = 0; i < n; i++)printf(" %d ", a[i]);printf("\n");
}
插入排序
插入排序（英语：Insertion Sort）是一种简单直观的排序算法。它的工作原理是通过构建有序序列，对于未排序数据，在已排序序列中从后向前扫描，找到相应位置并插入。插入排序在实现上，通常采用in-place排序），因而在从后向前扫描过程中，需要反复把已排序元素逐步向后挪位，为最新元素提供插入空间。
过程演示：
#include <stdio.h>int main(){int a[18] = {11,5,53,10,26,3,89,32,9,10,1,24,35,56,43,23,788,43};int i,j,k,n,tmp;n = sizeof(a) / sizeof(int);printf("n = %d\n", n);for (i = 1; i < n; i ++) {tmp = a[i];for (j = i; j > 0 && tmp < a[j - 1]; j--) {a[j] = a[j - 1];}a[j] = tmp;}for (i = 0; i < n; i++)printf(" %d ", a[i]);printf("\n");
}
希尔排序
希尔排序，也称递减增量排序算法，是插入排序的一种更高效的改进版本。希尔排序是非稳定排序算法。希尔排序是基于插入排序的以下两点性质而提出改进方法的：
插入排序在对几乎已经排好序的数据操作时，效率高，即可以达到线性排序的效率
但插入排序一般来说是低效的，因为插入排序每次只能将数据移动一位
#include <stdio.h>int main(){int a[18] = {11,5,53,10,26,3,89,32,9,10,1,24,35,56,43,23,788,43};int i,j,k,n,tmp;n = sizeof(a) / sizeof(int);printf("n = %d\n", n);for (k = n >> 1; k > 0; k = k >> 1)for (i = k; i < n; i ++) {tmp = a[i];for (j = i - k; j >= 0 && tmp < a[j]; j-= k) {a[j + k] = a[j];}a[j + k] = tmp;}for (i = 0; i < n; i++)printf(" %d ", a[i]);printf("\n");
}
归并排序
把数据分为两段，从两段中逐个选最小的元素移入新数据段的末尾。
int min(int x, int y) {return x < y ? x : y;}void merge_sort(int arr[], int len) {int* a = arr;int* b = (int*) malloc(len * sizeof(int));int seg, start;for (seg = 1; seg < len; seg += seg) {for (start = 0; start < len; start += seg + seg) {int low = start, mid = min(start + seg, len), high = min(start + seg + seg, len);int k = low;int start1 = low, end1 = mid;int start2 = mid, end2 = high;while (start1 < end1 && start2 < end2)b[k++] = a[start1] < a[start2] ? a[start1++] : a[start2++];while (start1 < end1)b[k++] = a[start1++];while (start2 < end2)b[k++] = a[start2++];}int* temp = a;a = b;b = temp;}if (a != arr) {int i;for (i = 0; i < len; i++)b[i] = a[i];b = a;}free(b);}
快速排序
在区间中随机挑选一个元素作基准，将小于基准的元素放在基准之前，大于基准的元素放在基准之后，再分别对小数区与大数区进行排序。
typedef struct _Range {int start, end;} Range;Range new_Range(int s, int e) {Range r;r.start = s;r.end = e;return r;}void swap(int *x, int *y) {int t = *x;*x = *y;*y = t;}void quick_sort(int arr[], const int len) {if (len <= 0)return; // 避免len等於負值時引發段錯誤（Segment Fault）// r[]模擬列表,p為數量,r[p++]為push,r[--p]為pop且取得元素Range r[len];int p = 0;r[p++] = new_Range(0, len - 1);while (p) {Range range = r[--p];if (range.start >= range.end)continue;int mid = arr[(range.start + range.end) / 2]; int left = range.start, right = range.end;do{while (arr[left] < mid) ++left; while (arr[right] > mid) --right; if (left <= right){swap(&arr[left],&arr[right]);left++;right--;}} while (left <= right);if (range.start < right) r[p++] = new_Range(range.start, right);if (range.end > left) r[p++] = new_Range(left, range.end);}}
