找到数组中第几个最小的数据

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找到数组中第几个最小的数据将经典的快速排序算法做简单修改即可

示例代码如下:

void testFindSpecificMin(){    int arr[] = {2, 4, 3, 9, 6, 5, 7, 0, 2, 1};    //int arr[] = {4, 2, 9};    //int arr[] = {0, 1, 2, 3, 4, 5, 6, 7, 8};    int position = 2;    findSpecificMin(arr, sizeof(arr)/sizeof(int), position - 1, 0);    printf("\n");    for (int i = 0; i < sizeof(arr)/sizeof(int); i++) {        printf("arr is %d\n", arr[i]);    }    printf("min is %d\n", arr[position - 1]);    for (int i = 1; i <= sizeof(arr)/sizeof(int); i++) {        int position = i;        findSpecificMin(arr, sizeof(arr)/sizeof(int), position - 1, 0);        printf("min is %d\n", arr[position - 1]);    }}/**  * currentPivot 当前枢纽元的位置 * specificMin 第几个最小的数 */void findSpecificMin(int arr[], int length, int specificMin, int currentPivot){    if (length <= 1) {        return;    }    if (length == 2) {        if (arr[0] > arr[1]) {            swap(arr, arr + 1);        }        return;    }    int center = (length - 1) / 2;    if (arr[0] > arr[length - 1]) {        swap(arr, arr + length - 1);    }    if (arr[0] > arr[center]) {        swap(arr, arr + center);    }    if (arr[center] > arr[length - 1]) {        swap(arr + center, arr + length - 1);    }    swap(arr + center, arr + length - 1);    int pivotElement = arr[length - 1];    int leftp = 0;    int rightp = length - 1;    while (1) {        while (arr[--rightp] > pivotElement) {        }        while (arr[++leftp] < pivotElement) {        }        if (rightp > leftp) {            swap(arr + rightp, arr + leftp);        }else{            break;        }    }    swap(arr + leftp, arr + length - 1);    printf("\n");    for (int i = 0; i < length; i++) {        printf("arr is %d\n", arr[i]);    }    if (currentPivot + leftp <= specificMin) {        findSpecificMin(arr + leftp, length - leftp, specificMin, currentPivot + leftp);    }else{        findSpecificMin(arr, leftp, specificMin, currentPivot);    }}

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