C排序演算法

標籤：

　　幾個常用的排序演算法：插入排序、快速排序、歸併排序

#include <stdio.h>#include <stdlib.h>#include <stdbool.h>/************************************************ * 插入排序法 * 第1次迴圈: 5, 3, 4, 6, 2, 1 -> 5, 5, 4, 6, 2, 1 -> 3, 5, 4, 6, 2, 1 * 第2次迴圈: 3, 5, 4, 6, 2, 1 -> 3, 5, 5, 6, 2, 1 -> 3, 4, 5, 6, 2, 1 * 第4次迴圈: 3, 4, 5, 6, 2, 1 -> 3, 3, 4, 5, 6, 1 -> 2, 3, 4, 5, 6, 1 * 第5次迴圈: 2, 3, 4, 5, 6, 1 -> 2, 2, 3, 4, 5, 6 -> 1, 2, 3, 4, 5, 6 ************************************************/void insert_sort(int *arr, int n){    int i = 0, j = 0, tmp = 0;    for( i = 1; i < n; i++ ){        if( arr[i-1] > arr[i] ){            tmp = arr[i];                for( j = i - 1; arr[j] > tmp && j >= 0 ; j-- ){                arr[j+1] = arr[j];            }            arr[j+1] = tmp;        }        /*        printf("the %d times iteration : ",i);        for( int j = 0 ; j < n; j++ ){            printf("%2d ",arr[j]);        }        printf("\n");        */    }}/************************************************ * 快速排序法 ************************************************/int partition(int *arr, int low, int high){    int tmp = arr[low];    while( low < high ){        while( low < high && arr[high]>= tmp ) high--;        arr[low] = arr[high];        while( low < high && arr[low] <= tmp ) low++;        arr[high] = arr[low];            }    arr[low] = tmp;    return low;}void q_sort(int *arr, int low, int high){    int pivot = 0;    while( low < high ){        pivot = partition( arr,low,high );    // 對arr一分為二        q_sort( arr,low,pivot-1 );            // 低子表遞迴排序        low = pivot + 1;                    // 尾遞迴    }}/************************************************ * 2分歸併排序 ************************************************/void merge_sort( int *arr,int *tmp,int s_idx,int m_idx,int e_idx){    int i = s_idx, j = m_idx+1, k = s_idx;    while( i != m_idx+1 && j != e_idx+1 ){        if( arr[i] < arr[j] ){            tmp[k++] = arr[i++];        }        else{            tmp[k++] = arr[j++];        }    }    while( i != m_idx+1 ){        tmp[k++] = arr[i++];    }    while( j != e_idx+1 ){        tmp[k++] = arr[j++];    }    for( i = s_idx;i <= e_idx;i++ ){        arr[i] = tmp[i];    }}void m_sort(int *arr,int *tmp,int s_idx,int e_idx){    if( s_idx < e_idx ){        int mid = (s_idx + e_idx) / 2;    // 將arr分為arr[0..mid]和arr[mid+1..n-1]        m_sort( arr,tmp,s_idx,mid);        // 遞迴將arr[0..mid]歸併為有序的tmp[0..mid]        m_sort( arr,tmp,mid+1,e_idx);    // 遞迴將arr[mid+1..n-1]歸併為有序的tmp[mid+1..n-1]        merge_sort( arr,tmp,s_idx,mid,e_idx);    // 將arr[0..mid]和arr[mid+1..n-1]歸併到tmp[0..n-1]    }}/************************************************ * 反轉序列 ************************************************/void reverse(int *arr, int n){    int s_idx = 0, e_idx = n - 1;    int tmp = 0;    while( s_idx < e_idx ){        tmp = arr[s_idx];        arr[s_idx++] = arr[e_idx];        arr[e_idx--] = tmp;    }}void show_arr(int *arr, int n){    for( int i = 0 ; i < n; i++ ){        printf("%2d ",arr[i]);    }    printf("\n");}/************************************************ * 二分尋找 * 數組 1  2  3  4  5  6  尋找 5 *      |     |        | *    low    mid       high * 迴圈1次： *     1  2  3  4  5  6  尋找 5 *              |  |  | *             low mid high ************************************************/bool binary_search(int *arr, int n, int key){    if( NULL == arr ) return false;    int low = 0, high = n - 1, mid = 0;    // low為數組首位，high為數組末位    while( low < high ){        mid = low + (( high - low ) >> 1); //防止溢出，移位也更高效。每次迴圈都要更新。        if( key < arr[mid] ){            // 若關鍵字小於中值            high = mid - 1;                // 高下標調整到中下標小1        }        else if( key > arr[mid] ){        // 若關鍵字大於中值            low = mid + 1;                // 低下標調整到中下標加1        }        else{            return true;        }    }    return false;}int main(){    int i = 0;    int arr[] = {5, 3, 4, 6, 2, 1, };    int len = sizeof(arr)/sizeof(arr[0]);    int tmp[len];    m_sort(arr,tmp,0,len-1);    printf("m_sort:\n");    show_arr(arr,len);        reverse(arr,len);    insert_sort(arr,len);    printf("insert_sort:\n");    show_arr(arr,len);        reverse(arr,len);    q_sort(arr,0,len-1);    printf("q_sort:\n");    show_arr(arr,len);        int key = 5;    printf("%d is%s in the arr\n",key,( binary_search(arr,len,key) ) ? "" : " not");}

 

　　輸出：

m_sort:
1 2 3 4 5 6
insert_sort:
1 2 3 4 5 6
q_sort:
1 2 3 4 5 6

5 is in the arr

C排序演算法