常用排序算法总结

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常用排序算法：冒泡选择直接插入二分插入希尔排序快速排序归并排序堆排序
算法的时间复杂度和空间复杂度就不分析了，自行百度，代码如下：
#include<iostream>#include<string>using namespace std;void bubble_sort1(int arr[], int len){    for(int i = 0; i < len-1; i++){        for(int j = len-1; j > i; j--){            if(arr[j] < arr[j-1]){                int tmp = arr[j];                arr[j] = arr[j-1];                arr[j-1] = tmp;            }        }    }}void bubble_sort2(int arr[], int len){    for(int i = len-1; i > 0; i--){        for(int j = 0; j < i; j++){            if(arr[j] > arr[j+1]){                int tmp = arr[j];                arr[j] = arr[j+1];                arr[j+1] = tmp;            }        }    }}void selectSort(int arr[], int len){    for(int i = 0; i < len-1; i++){        int index = i;        for(int j = i+1; j < len; j++){            if(arr[j] < arr[index])                index = j;        }        if(index != i){            int tmp = arr[i];            arr[i] = arr[index];            arr[index] = tmp;        }    }}//选择排序交换的次数比冒泡排序少很多void insert_sort(int arr[], int len){    for(int i = 1; i < len; i++){        int key = arr[i];        int j = i-1;        while(j >= 0 && arr[j] > key){            arr[j+1] = arr[j];            j--;        }        arr[j+1] = key;    }} //直接插入排序int binarySearch(int start, int end, int arr[], int target){    while(start < end){        int mid = (start+end)/2;        if(arr[mid] < target)            start = mid+1;        else            end = mid-1;    }    return start;}//二分插入排序void binary_sort(int arr[], int len){    for(int i = 1; i < len; i++){        int key = arr[i];        if(arr[i-1] > key){            int index = binarySearch(0, i-1, arr, key);            for(int j = i; j > index; j--)                arr[j] = arr[j-1];            arr[index] = key;        }    }}// shell 排序 希尔排序 先按步长n进行分组，然后插入排序，然后再减小步长，在进行分组插入排序，一直到步长为n=1为止void shellSort1(int arr[], int len){    for(int gap = len/2; gap > 0; gap /= 2){        for(int i = 0; i < gap; i++){            for(int j = i+gap; j < len; j += gap){                if(arr[j] < arr[j-gap]){                    int key = arr[j];                    int k = j-gap;                    while(k >= 0 && arr[k] > key){                        arr[k+gap] = arr[k];                        k -= gap;                    }                    arr[k+gap] = key;                }            }        }    }}// shellSort1 代码简化，将后两个for循环简化成一个for循环void shellSort2(int arr[], int len){    for(int gap = len/2; gap > 0; gap /= 2){        for(int j = gap; j < len; j++){            if(arr[j] < arr[j-gap]){                int tmp = arr[j];                int k = j - gap;                while(k >= 0 && arr[k] > tmp){                    arr[k+gap] = arr[k];                    k -= gap;                }                arr[k+gap] = tmp;            }        }    }}//快速排序算法void quick_sort(int arr[], int left, int right){    if(left < right){        int i = left, j = right, target = arr[left];        while(i < j){            while(i < j && arr[j] > target){                j--;            }            if(i < j) arr[i++] = arr[j];            while(i < j && arr[i] < target)                i++;            if(i < j) arr[j--] = arr[i];        }        arr[i] = target;        quick_sort(arr, left, i-1);        quick_sort(arr, i+1, right);    }}void merge(int arr[], int tmpArr[], int start, int mid, int end){    int i = start, j = mid+1;    int k = 0;    while(i <= mid && j <= end){        if(arr[i] > arr[j])            tmpArr[k++] = arr[j++];        else            tmpArr[k++] = arr[i++];    }    while(i <= mid){        tmpArr[k++] = arr[i++];    }    while(j <= end){        tmpArr[k++] = arr[j++];    }    for(i = 0; i < k; i++){        arr[start+i] = tmpArr[i];    }}void mergeSort(int arr[], int start, int end, int tmpArr[]){    if(start < end){        int mid = (start+end)/2;        mergeSort(arr, start, mid, tmpArr);        mergeSort(arr, mid+1, end, tmpArr);        merge(arr, tmpArr, start, mid, end);    }}int main(){    int arr[] = {2,4,3,2,6,7};    //binary_sort(arr, 6);    //shellSort2(arr, 6);    int tmpArr[6];    mergeSort(arr, 0, 5, tmpArr);    //quick_sort(arr, 0, 5);    for(int i = 0; i < 6; i++) cout << arr[i] << endl;}
快速排序算法有很多优化方式，比如随机选取基准点，对区间比较小的不使用快速排序，以免递归深度过深。
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