各类排序算法集合

#import "SortFunction.h"

1.//冒泡排序（bubble sort） — O(n2)
void bubbleSort(int array[],int count){
    for (int i = 0; i < count - 1; i++) {
        for (int j = 0; j < count - i - 1; j++) {
            if (array[j] < array[j+1]) {
                swap(array + j,array + j + 1);
            }
        }
    }
}

2.//选择排序(Selection sort) - O(n2)
void selectionSort(int array[],int count){
    for (int i = 0;i < count - 1 ; i++) {
        int minIndex = i;
        for (int j = i + 1; j < count; j++) {
            if (array[j] < array[minIndex]) {
                minIndex = j;
            }
        }
        if (minIndex != i) {    //如何最小值索引与 i 不同的机会多不用判断效率更高
            swap(array + i, array + minIndex);
        }
    }
}

3.//插入排序（insertion sort）— O(n2)
void insertionSort(int array[],int count){
    for (int i = 1; i < count; i++) {
        int temp = array[i];
        int j = i - 1;
        while (j >= 0 && array[j] > temp) {
            array[j + 1] = array[j];
            j--;
        }
        array[j + 1] = temp;
    }
}

4.//合併排序（merge sort）— O(n log n); 需要 O(n) 額外空間(两路归并)
void mergeSort2w(int array[],int count){
    int mid = count / 2;
    int temp[count];
   
    int * pLeft = temp;
    int * pRight = temp + mid;
    int leftCount = mid;
    int rightCount = count - mid;
   
    for (int i = 0; i < count; i++) {
        temp[i] = array[i];
    }
   
    bubbleSort(pLeft, leftCount);
    bubbleSort(pRight, rightCount);
   
    //开始归并排序
    int i = 0;      //排序数组索引
    int j = 0;      //左数组索引
    int k = 0;      //右数组索引
    while (j < leftCount && k < rightCount) {
        if (pLeft[j] < pRight[k]) {
            array[i++] = pLeft[j++];
        }else{
            array[i++] = pRight[k++];
        }
    }
   
    while (j < leftCount) {
        array[i++] = pLeft[j++];
    }
   
    while (k < rightCount) {
        array[i++] = pRight[k++];
    }
}

5.//快速排序（quicksort）— O(n log n) 期望時間, O(n2) 最壞情況; 對於大的、亂數串列一般相信是最快的已知排序
void quickSort(int array[],int count){
    if (count > 1) {
        int i = 0;
        int j = count - 1;
        int temp = array[i];
        while (i < j) {
            while (i < j && array[j] >= temp) {  //向右查找比temp小的值
                j--;
            }
            if (i < j) {
                array[i++] = array[j];
            }
            while (i < j && array[i] < temp) { //向左查找比temp大的值,不能有等于
                i++;
            }
            if (i < j) {
                array[j--] = array[i];
            }
            array[i] = temp;
        }
        quickSort(array, i);
        quickSort(array + i + 1, count - i - 1);
    }
}



6.//交换两个数的值
void swap(int * x,int * y){
    int temp = 0;
    temp = *x;
    *x = *y;
    *y = temp;
}

7.//遍历数组输出
void printArray(int array[],int count){
    for (int i = 0 ; i < count; i++) {
        printf("%d : %d \n",i,array[i]);
    }
}

8.//折半查找,时间复杂度为o(log(n))
int halfSeek(int array[],int count,int number){
    int start = 0;
    int end = count - 1;
    int mid = (end + start) / 2;
   
    while (array[mid] != number && start < end) {
        if (array[mid] > number) {
            end = mid - 1;
        }else{
            start = mid + 1;
        }
        mid = (end + start) / 2;
    }
    if (array[mid] == number) {
        printf("%d\n",mid);
        return mid;
    }else{
        printf("not found\n");
       
    }
    return -1;
}

9.//手动输入一个一维数组并显示结果

int main(int argc, constchar * argv[])

{
   
    int a[5]={0};
   
    printf("input 5 numbers \n");
   
    for ( int i =0; i<5;i++) {
        scanf("%d",&a[i]);
    }
   
    for (int i =0; i<5; i++) {
        printf("%d \n",a[i]);
    }