下面是一个使用C语言实现的几个常见算法示例，包括排序算法（冒泡排序、快速排序）、查找算法（二分查找）以及递归算法（斐波那契数列）。
1. 冒泡排序（Bubble Sort）
#include <stdio.h>
void bubbleSort(int arr[], int n) {
for (int i = 0; i < n-1; i++) {
for (int j = 0; j < n-i-1; j++) {
if (arr[j] > arr[j+1]) {
// 交换元素
int temp = arr[j];
arr[j] = arr[j+1];
arr[j+1] = temp;
}
}
}
}
int main() {
int arr[] = {64, 34, 25, 12, 22, 11, 90};
int n = sizeof(arr)/sizeof(arr[0]);
bubbleSort(arr, n);
printf("Sorted array: \n");
for (int i = 0; i < n; i++) {
printf("%d ", arr[i]);
}
return 0;
}
2. 快速排序（Quick Sort）
#include <stdio.h>
void swap(int* a, int* b) {
int t = *a;
*a = *b;
*b = t;
}
int partition(int arr[], int low, int high) {
int pivot = arr[high];
int i = (low - 1);
for (int j = low; j <= high - 1; j++) {
if (arr[j] < pivot) {
i++;
swap(&arr[i], &arr[j]);
}
}
swap(&arr[i + 1], &arr[high]);
return (i + 1);
}
void quickSort(int arr[], int low, int high) {
if (low < high) {
int pi = partition(arr, low, high);
quickSort(arr, low, pi - 1);
quickSort(arr, pi + 1, high);
}
}
int main() {
int arr[] = {10, 7, 8, 9, 1, 5};
int n = sizeof(arr)/sizeof(arr[0]);
quickSort(arr, 0, n-1);
printf("Sorted array: \n");
for (int i = 0; i < n; i++) {
printf("%d ", arr[i]);
}
return 0;
}
3. 二分查找（Binary Search）
#include <stdio.h>
int binarySearch(int arr[], int l, int r, int x) {
while (l <= r) {
int m = l + (r - l) / 2;
if (arr[m] == x)
return m;
if (arr[m] < x)
l = m + 1;
else
r = m - 1;
}
return -1;
}
int main() {
int arr[] = {2, 3, 4, 10, 40};
int n = sizeof(arr)/sizeof(arr[0]);
int x = 10;
int result = binarySearch(arr, 0, n-1, x);
if (result == -1)
printf("Element is not present in array\n");
else
printf("Element is present at index %d\n", result);
return 0;
}
4. 斐波那契数列（Fibonacci Sequence）
#include <stdio.h>
int fibonacci(int n) {
if (n <= 1)
return n;
return fibonacci(n-1) + fibonacci(n-2);
}
int main() {
int n = 10;
printf("Fibonacci sequence up to %d terms: \n", n);
for (int i = 0; i < n; i++) {
printf("%d ", fibonacci(i));
}
return 0;
}
5. 插入排序（Insertion Sort）
#include <stdio.h>
void insertionSort(int arr[], int n) {
int i, key, j;
for (i = 1; i < n; i++) {
key = arr[i];
j = i - 1;
while (j >= 0 && arr[j] > key) {
arr[j + 1] = arr[j];
j = j - 1;
}
arr[j + 1] = key;
}
}
int main() {
int arr[] = {12, 11, 13, 5, 6};
int n = sizeof(arr)/sizeof(arr[0]);
insertionSort(arr, n);
printf("Sorted array: \n");
for (int i = 0; i < n; i++) {
printf("%d ", arr[i]);
}
return 0;
}
6. 选择排序（Selection Sort）
#include <stdio.h>
void swap(int *xp, int *yp) {
int temp = *xp;
*xp = *yp;
*yp = temp;
}
void selectionSort(int arr[], int n) {
int i, j, min_idx;
for (i = 0; i < n-1; i++) {
min_idx = i;
for (j = i+1; j < n; j++)
if (arr[j] < arr[min_idx])
min_idx = j;
swap(&arr[min_idx], &arr[i]);
}
}
int main() {
int arr[] = {64, 25, 12, 22, 11};
int n = sizeof(arr)/sizeof(arr[0]);
selectionSort(arr, n);
printf("Sorted array: \n");
for (int i = 0; i < n; i++) {
printf("%d ", arr[i]);
}
return 0;
}
7. 归并排序（Merge Sort）
#include <stdio.h>
#include <stdlib.h>
void merge(int arr[], int l, int m, int r) {
int i, j, k;
int n1 = m - l + 1;
int n2 = r - m;
int L[n1], R[n2];
for (i = 0; i < n1; i++)
L[i] = arr[l + i];
for (j = 0; j < n2; j++)
R[j] = arr[m + 1 + j];
i = 0;
j = 0;
k = l;
while (i < n1 && j < n2) {
if (L[i] <= R[j]) {
arr[k] = L[i];
i++;
} else {
arr[k] = R[j];
j++;
}
k++;
}
while (i < n1) {
arr[k] = L[i];
i++;
k++;
}
while (j < n2) {
arr[k] = R[j];
j++;
k++;
}
}
void mergeSort(int arr[], int l, int r) {
if (l < r) {
int m = l + (r - l) / 2;
mergeSort(arr, l, m);
mergeSort(arr, m + 1, r);
merge(arr, l, m, r);
}
}
int main() {
int arr[] = {12, 11, 13, 5, 6, 7};
int arr_size = sizeof(arr)/sizeof(arr[0]);
printf("Given array is \n");
for (int i = 0; i < arr_size; i++)
printf("%d ", arr[i]);
mergeSort(arr, 0, arr_size - 1);
printf("\nSorted array is \n");
for (int i = 0; i < arr_size; i++)
printf("%d ", arr[i]);
return 0;
}
8. 堆排序（Heap Sort）
#include <stdio.h>
void swap(int *a, int *b) {
int temp = *a;
*a = *b;
*b = temp;
}
void heapify(int arr[], int n, int i) {
int largest = i;
int left = 2 * i + 1;
int right = 2 * i + 2;
if (left < n && arr[left] > arr[largest])
largest = left;
if (right < n && arr[right] > arr[largest])
largest = right;
if (largest != i) {
swap(&arr[i], &arr[largest]);
heapify(arr, n, largest);
}
}
void heapSort(int arr[], int n) {
for (int i = n / 2 - 1; i >= 0; i--)
heapify(arr, n, i);
for (int i = n - 1; i > 0; i--) {
swap(&arr[0], &arr[i]);
heapify(arr, i, 0);
}
}
int main() {
int arr[] = {12, 11, 13, 5, 6, 7};
int n = sizeof(arr)/sizeof(arr[0]);
heapSort(arr, n);
printf("Sorted array is \n");
for (int i = 0; i < n; i++)
printf("%d ", arr[i]);
return 0;
}
9. 线性查找（Linear Search）
#include <stdio.h>
int linearSearch(int arr[], int n, int x) {
for (int i = 0; i < n; i++) {
if (arr[i] == x)
return i;
}
return -1;
}
int main() {
int arr[] = {2, 3, 4, 10, 40};
int n = sizeof(arr)/sizeof(arr[0]);
int x = 10;
int result = linearSearch(arr, n, x);
if (result == -1)
printf("Element is not present in array\n");
else
printf("Element is present at index %d\n", result);
return 0;
}
10. 递归求阶乘（Factorial）
#include <stdio.h>
int factorial(int n) {
if (n == 0)
return 1;
return n * factorial(n - 1);
}
int main() {
int n = 5;
printf("Factorial of %d is %d\n", n, factorial(n));
return 0;
}
11. 递归求最大公约数（GCD）
#include <stdio.h>
int gcd(int a, int b) {
if (b == 0)
return a;
return gcd(b, a % b);
}
int main() {
int a = 60, b = 48;
printf("GCD of %d and %d is %d\n", a, b, gcd(a, b));
return 0;
}
12. 递归求幂（Power）
#include <stdio.h>
double power(double base, int exp) {
if (exp == 0)
return 1;
if (exp > 0)
return base * power(base, exp - 1);
return 1 / power(base, -exp);
}
int main() {
double base = 2.0;
int exp = 3;
printf("%.2f^%d = %.2f\n", base, exp, power(base, exp));
return 0;
}
13. 递归求数组和（Array Sum）
#include <stdio.h>
int arraySum(int arr[], int n) {
if (n <= 0)
return 0;
return arr[n-1] + arraySum(arr, n-1);
}
int main() {
int arr[] = {1, 2, 3, 4, 5};
int n = sizeof(arr)/sizeof(arr[0]);
printf("Sum of array is %d\n", arraySum(arr, n));
return 0;
}
14. 递归求数组最大值（Array Max）
#include <stdio.h>
int arrayMax(int arr[], int n) {
if (n == 1)
return arr[0];
int max = arrayMax(arr, n-1);
return (arr[n-1] > max) ? arr[n-1] : max;
}
int main() {
int arr[] = {1, 2, 3, 4, 5};
int n = sizeof(arr)/sizeof(arr[0]);
printf("Max of array is %d\n", arrayMax(arr, n));
return 0;
}
15. 递归求数组最小值（Array Min）
#include <stdio.h>
int arrayMin(int arr[], int n) {
if (n == 1)
return arr[0];
int min = arrayMin(arr, n-1);
return (arr[n-1] < min) ? arr[n-1] : min;
}
int main() {
int arr[] = {1, 2, 3, 4, 5};
int n = sizeof(arr)/sizeof(arr[0]);
printf("Min of array is %d\n", arrayMin(arr, n));
return 0;
}
16. 递归求数组平均值（Array Average）
#include <stdio.h>
double arrayAverage(int arr[], int n) {
if (n == 1)
return arr[0];
return (arr[n-1] + (n-1) * arrayAverage(arr, n-1)) / n;
}
int main() {
int arr[] = {1, 2, 3, 4, 5};
int n = sizeof(arr)/sizeof(arr[0]);
printf("Average of array is %.2f\n", arrayAverage(arr, n));
return 0;
}
17. 递归求数组逆序（Array Reverse）
#include <stdio.h>
void arrayReverse(int arr[], int start, int end) {
if (start >= end)
return;
int temp = arr[start];
arr[start] = arr[end];
arr[end] = temp;
arrayReverse(arr, start+1, end-1);
}
int main() {
int arr[] = {1, 2, 3, 4, 5};
int n = sizeof(arr)/sizeof(arr[0]);
arrayReverse(arr, 0, n-1);
printf("Reversed array is \n");
for (int i = 0; i < n; i++)
printf("%d ", arr[i]);
return 0;
}
18. 递归求数组是否有序（Array Sorted）
#include <stdio.h>
int isArraySorted(int arr[], int n) {
if (n == 1)
return 1;
if (arr[n-1] < arr[n-2])
return 0;
return isArraySorted(arr, n-1);
}
int main() {
int arr[] = {1, 2, 3, 4, 5};
int n = sizeof(arr)/sizeof(arr[0]);
if (isArraySorted(arr, n))
printf("Array is sorted\n");
else
printf("Array is not sorted\n");
return 0;
}
19. 递归求数组是否包含元素（Array Contains）
#include <stdio.h>
int arrayContains(int arr[], int n, int x) {
if (n == 0)
return 0;
if (arr[n-1] == x)
return 1;
return arrayContains(arr, n-1, x);
}
int main() {
int arr[] = {1, 2, 3, 4, 5};
int n = sizeof(arr)/sizeof(arr[0]);
int x = 3;
if (arrayContains(arr, n, x))
printf("Array contains %d\n", x);
else
printf("Array does not contain %d\n", x);
return 0;
}
20. 递归求数组元素个数（Array Count）
#include <stdio.h>
int arrayCount(int arr[], int n, int x) {
if (n == 0)
return 0;
if (arr[n-1] == x)
return 1 + arrayCount(arr, n-1, x);
return arrayCount(arr, n-1, x);
}
int main() {
int arr[] = {1, 2, 3, 4, 5, 3};
int n = sizeof(arr)/sizeof(arr[0]);
int x = 3;
printf("Array contains %d occurrences of %d\n", arrayCount(arr, n, x), x);
return 0;
}
21. 递归求数组元素位置（Array Index）
#include <stdio.h>
int arrayIndex(int arr[], int n, int x) {
if (n == 0)
return -1;
if (arr[n-1] == x)
return n-1;
return arrayIndex(arr, n-1, x);
}
int main() {
int arr[] = {1, 2, 3, 4, 5};
int n = sizeof(arr)/sizeof(arr[0]);
int x = 3;
int index = arrayIndex(arr, n, x);
if (index == -1)
printf("Array does not contain %d\n", x);
else
printf("Array contains %d at index %d\n", x, index);
return 0;
}
