各种排序算法代码（C语言版）

#include <stdio.h>
/*
 * 选择排序
 * 稳定性：不稳定
 * 时间复杂度：O(N^2)
**/

void select_sort(int a[], int l, int r)
{
    for (int m_v, m_idx, t, i = l; i < r; ++i) {
        m_v = a[i]; m_idx = i;
        for (int j = i + 1; j < r; ++j) {
            if (m_v > a[j]) {
                m_v = a[j];
                m_idx = j;
            }
        }
        t = a[i]; a[i] = a[m_idx]; a[m_idx] = t;
    }
}

int main(void)
{
    int a[100];
    int n; scanf("%d", &n);
    for (int i = 0; i < n; ++i) scanf("%d", &a[i]);
    select_sort(a, 0, n);
    for (int i = 0; i < n; ++i) printf("%d ", a[i]);
    return 0;
}

#include <stdio.h>
/*
 * 冒泡排序
 * 稳定性：稳定
 * 时间复杂度：O(N^2)
**/

void bubble_sort(int a[], int l, int r)
{
    for (int i = l; i < r; ++i) {
        for (int j = l; j < r - i - 1; ++j) {
            if (a[j] > a[j + 1]) {
                int tmp = a[j];
                a[j] = a[j + 1];
                a[j + 1] = tmp;
            }
        }
    }
}

int main(void)
{
    int a[100];
    int n; scanf("%d", &n);
    for (int i = 0; i < n; ++i) scanf("%d", &a[i]);
    bubble_sort(a, 0, n);
    for (int i = 0; i < n; ++i) printf("%d ", a[i]);
    return 0;
}

#include <stdio.h>
/*
 * 插入排序
 * 稳定性：稳定
 * 时间复杂度： O(N^2)
**/
void insert_sort(int a[], int l, int r)
{
    for (int tmp, j, i = l + 1; i < r; ++i) {
        tmp = a[i], j = i - 1;
        while (j >= l && tmp < a[j]) a[j+1] = a[j--];
        a[j+1] = tmp;
    }
}

int main(void)
{
    int a[100];
    int n; scanf("%d", &n);
    for (int i = 0; i < n; ++i) scanf("%d", &a[i]);
    insert_sort(a, 0, n);
    for (int i = 0; i < n; ++i) printf("%d ", a[i]);
    return 0;
}

#include <stdio.h>
/*
 * 希尔排序
 * 稳定性：不稳定
 * 时间复杂度：O(N*logN)
**/

void shell_insert_sort(int a[], int l, int r, int d)
{
    for (int tmp, j, i = l + d; i < r; ++i) {
        tmp = a[i], j = i - d;
        while (j >= l && tmp < a[j]) {
            a[j + d] = a[j];
            j -= d;
        }
        a[j + d] = tmp;
    }
}

void shell_sort(int a[], int l, int r)
{
    int d = (r - l) / 2;
    while (d >= 1) {
        shell_insert_sort(a, l, r, d);
        d /= 2;
    }
}

int main(void)
{
    int a[100];
    int n; scanf("%d", &n);
    for (int i = 0; i < n; ++i) scanf("%d", &a[i]);
    shell_sort(a, 0, n);
    for (int i = 0; i < n; ++i) printf("%d ", a[i]);
    return 0;
}

#include <stdio.h>
/*
 * 堆排序
 * 稳定性：不稳定
 * 时间复杂度：O(N*logN)
**/

// big top pile
void heap_adjust(int a[], int fa, int n)
{
    int cd = fa * 2 + 1;
    int tmp = a[fa];
    while (cd < n) {
        if (cd + 1 < n && a[cd] < a[cd + 1]) cd++;
        if (a[fa] >= a[cd]) break;
        a[fa] = a[cd];
        fa = cd;
        cd = fa * 2 + 1;
        a[fa] = tmp;
    }
}

void build_heap(int a[], int n)
{
    // ignore leap node
    for (int i = (n - 1) / 2; i >= 0; --i) {
        heap_adjust(a, i, n);
    }
}


void heap_sort(int a[], int l, int r)
{
    build_heap(a + l, r - l);
    for (int tmp, i = r - 1; i > l; --i) {
        tmp = a[i]; a[i] = a[0]; a[0] = tmp;
        heap_adjust(a + l, 0, i);
    }
}

int main(void)
{
    int a[100];
    int n; scanf("%d", &n);
    for (int i = 0; i < n; ++i) scanf("%d", &a[i]);
    heap_sort(a, 0, n);
    for (int i = 0; i < n; ++i) printf("%d ", a[i]);
    return 0;
}