经典排序算法的实现（选择，插入，shell，堆，快速，归并排序）

1.选择排序

//选择排序
void selectSort(int * arr, int n) {
for (int i = 0; i < n - 1; i++) {
int min = arr[i];
int minPos = i;
for (int j = i + 1; j < n; j++) {
if (min > arr[j]) {
min = arr[j];
minPos = j;
}
}

int temp = arr[i];
arr[i] = arr[minPos];
arr[minPos] = temp;
}
}

2.插入排序

//插入排序
void insertSort(int * arr, int n) {
for (int i = 1; i < n; i++) {
int k = arr[i];
int j = i - 1;

while (j >= 0 && arr[j] > k) {
arr[j+1] = arr[j];
j--;
}
arr[j+1] = k;
}
}

3.shell排序

//shell排序,优化插排
void shellSort(int * arr, int n) {
int step = n;
while (step > 1) {
step = step / 2;
for (int i = step; i < n; i++) {
int temp = arr[i];
int j = i;
while (j - step >= 0 && temp <arr[j - step]) {
arr[j] = arr[j-step];
j -= step;
}
arr[j] = temp;
}
}
}

4.堆排序

//堆排序,优化选排
void headJust(int * arr, int start, int n) {
int temp = arr[start];
int child = 2 * start + 1;

while (child < n) {
if (child+1 < n && arr[child] < arr[child+1]) {
child++;
}

if (temp >= arr[child]) {
break;
}

arr[start] = arr[child];

start = child;
child = child * 2 + 1;
}

arr[start] = temp;
}

void headSort(int * arr, int n) {
for (int i = n / 2; i >= 0; i--) {
headJust(arr, i, n);
}

for (int i = 1; i < n; i++) {
int temp = arr[0];				//首元素与最后元素进行交换
arr[0] = arr[n-i];
arr[n-i] = temp;
headJust(arr, 0, n-i);			//继续调整为最大堆
}
}

5.归并排序

//归并排序,分而治之
void merge(int * arr, int first, int mid, int last) {
int i = first, j = mid+1;
int m = mid, n = last;
int k = 0;
int temp[SIZE];
while (i <= m && j <= n) {
temp[k++] = (arr[i] <= arr[j])?arr[i++]:arr[j++];
}

while (i <= m) {
temp[k++] = arr[i++];
}

while (j <= n) {
temp[k++] = arr[j++];
}

for (int i = 0; i < k; i++) {
arr[i+first] = temp[i];
}
}

void mergeSort(int * arr, int start, int end) {
if (start < end) {
int mid = (start+end) / 2;
mergeSort(arr, start, mid);
mergeSort(arr, mid+1, end);
merge(arr, start, mid, end);
}
}

6.快速排序

//快速排序,挖坑填数分治法
void quickSort(int * arr, int left, int right) {
if (left < right) {
int i = left;
int j = right-1;
int temp = arr[i];

while (i < j) {
while (i < j && arr[j] >= temp)
j--;
if (i < j) {
arr[i++] = arr[j];
}

while (i < j && arr[i] < temp)
i++;
if (i < j) {
arr[j--] = arr[i];
}
}

arr[i] = temp;
quickSort(arr, left, i-1);
quickSort(arr, i+1, right);
}
}

具体实现如下

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define SIZE 200

//快速排序,挖坑填数分治法
void quickSort(int * arr, int left, int right) {
if (left < right) {
int i = left;
int j = right;
int temp = arr[i];

while (i < j) {
while (i < j && arr[j] >= temp)
j--;
if (i < j) {
arr[i++] = arr[j];
}

while (i < j && arr[i] < temp)
i++;
if (i < j) {
arr[j--] = arr[i];
}
}

arr[i] = temp;
quickSort(arr, left, i-1);
quickSort(arr, i+1, right);
}
}

//归并排序,分而治之
void merge(int * arr, int first, int mid, int last) {
int i = first, j = mid+1;
int m = mid, n = last;
int k = 0;
int temp[SIZE];
while (i <= m && j <= n) {
temp[k++] = (arr[i] <= arr[j])?arr[i++]:arr[j++];
}

while (i <= m) {
temp[k++] = arr[i++];
}

while (j <= n) {
temp[k++] = arr[j++];
}

fo
4000
r (int i = 0; i < k; i++) {
arr[i+first] = temp[i];
}
}

void mergeSort(int * arr, int start, int end) {
if (start < end) {
int mid = (start+end) / 2;
mergeSort(arr, start, mid);
mergeSort(arr, mid+1, end);
merge(arr, start, mid, end);
}
}

//堆排序,优化选排
void headJust(int * arr, int start, int n) {
int temp = arr[start];
int child = 2 * start + 1;

while (child < n) {
if (child+1 < n && arr[child] < arr[child+1]) {
child++;
}

if (temp >= arr[child]) {
break;
}

arr[start] = arr[child];

start = child;
child = child * 2 + 1;
}

arr[start] = temp;
}

void headSort(int * arr, int n) {
for (int i = n / 2; i >= 0; i--) {
headJust(arr, i, n);
}

for (int i = 1; i < n; i++) {
int temp = arr[0]; //首元素与最后元素进行交换
arr[0] = arr[n-i];
arr[n-i] = temp;
headJust(arr, 0, n-i); //继续调整为最大堆
}
}

//shell排序,优化插排 void shellSort(int * arr, int n) { int step = n; while (step > 1) { step = step / 2; for (int i = step; i < n; i++) { int temp = arr[i]; int j = i; while (j - step >= 0 && temp <arr[j - step]) { arr[j] = arr[j-step]; j -= step; } arr[j] = temp; } } }

//插入排序 void insertSort(int * arr, int n) { for (int i = 1; i < n; i++) { int k = arr[i]; int j = i - 1; while (j >= 0 && arr[j] > k) { arr[j+1] = arr[j]; j--; } arr[j+1] = k; } }

//选择排序 void selectSort(int * arr, int n) { for (int i = 0; i < n - 1; i++) { int min = arr[i]; int minPos = i; for (int j = i + 1; j < n; j++) { if (min > arr[j]) { min = arr[j]; minPos = j; } } int temp = arr[i]; arr[i] = arr[minPos]; arr[minPos] = temp; } }

void initialArray(int * arr, int n) {
for (int i = 0; i < n; i++) {
arr[i] = rand() % 100 + 1;
}
}

void printNum(int * arr, int n) {
for (int i = 0; i < n; i++) {
if ((i+1) % 10 == 0) {
putchar('\n');
} else {
printf("%d\t", arr[i]);
}
}
}

int main(void)
{
srand((unsigned) time(NULL));
int num[SIZE];

printf("选择排序前:\n");
initialArray(num, SIZE);
printNum(num, SIZE);
printf("选择排序后:\n");
selectSort(num, SIZE);
printNum(num, SIZE);

printf("插入排序前:\n");
initialArray(num, SIZE);
printNum(num, SIZE);
printf("插入排序后:\n");
insertSort(num, SIZE);
printNum(num, SIZE);

printf("shell排序前:\n");
initialArray(num, SIZE);
printNum(num, SIZE);
printf("shell排序后:\n");
shellSort(num, SIZE);
printNum(num, SIZE);

printf("堆排序前:\n");
initialArray(num, SIZE);
printNum(num, SIZE);
printf("堆排序后:\n");
headSort(num, SIZE);
printNum(num, SIZE);

printf("归并排序前:\n");
initialArray(num, SIZE);
printNum(num, SIZE);
printf("归并排序后:\n");
mergeSort(num, 0, SIZE-1);
printNum(num, SIZE);

printf("快速排序前:\n");
initialArray(num, SIZE);
printNum(num, SIZE);
printf("快速排序后:\n");
quickSort(num, 0, SIZE-1);
printNum(num, SIZE);

return 0;
}