双向冒泡

//双向冒泡
void  DoubleBubble(ElemType A[], int n) {
    int i,temp;
    int low = 0, high = n - 1;
    int flag = 1;//一次冒泡后记录元素是否交换标志
    while (low < high&&flag) {//循环跳出条件中当flag=0时说明已没有逆序
        flag = 0;
        for(i=low;i<high;i++)
            if (A[i] > A[i + 1]) {
                temp = A[i+1];
                A[i + 1] = A[i];
                A[i] = temp;
                flag = 1;
            }
        high--;
        for(i=high;i>low;i--)
            if (A[i] < A[i - 1]) {
                temp = A[i - 1];
                A[i - 1] = A[i];
                A[i] = temp;
                flag = 1;
            }
        low++;
    }
}
//把所有奇数移到偶数前，先从前向后找到一个偶数元素，再从后向前找到一个奇数元素
void move(ElemType A[], int len) {
    int temp;
    int i = 0, j = len - 1;
    while (i < j) {
        while (i < j && A[i] % 2 != 0)
            i++;
        while (i < j && A[j] % 2 != 1)
            j--;
        if (i < j) {
            temp = A[i];
            A[i] = A[j];
            A[j] = temp;
            i++;
            j--;
        }
    }
}
//随机求出枢轴的下标，然后将枢轴值与A[low]交换
int Partition(ElemType A[], int low, int high) {
    int rand_Index = low + rand() % (high - low + 1);
    swap(A[rand_Index],A[low]);
    ElemType pivot = A[low];
    int i = low;
    for (int j = low + 1; j <=high; j++)
        if (A[j] < pivot)
            swap(A[++i], A[j]);
    swap(A[i], A[low]);
    return i;        
}
//找出第k小的元素
int Mink(int A[], int low, int high, int k) {
    int pivot = A[low];
    int low_temp = low;
    int high_temp = high;
    while (low < high) {
        while (low<high && A[high]>=pivot)
            --high;
        A[low] = A[high];
        while (low < high && A[low] <= pivot)
            ++low;
        A[high] = A[low];
    }
    A[low] = pivot;
    if (low == k)
        return A[low];
    else if (low > k)
        return Mink(A, low_temp, low - 1, k);
    else
        return Mink(A, low + 1, high_temp, k);
}
int SetPartition(int A[], int n) {
    int pivotkey, low = 0, low0 = 0, high = n - 1, high0 = n - 1, flag = 1, k = n / 2, i;
    int s1 = 0, s2 = 0;
    while (flag) {
        pivotkey = A[low];
        while (low < high) {
            while (low < high && A[high] >= pivotkey)
                --high;
            if (low != high)
                A[low] = A[high];
            while (low < high && A[low] <= pivotkey)
                ++low;
            if (low != high)
                A[high] = A[low];
        }
        A[low] = pivotkey;
        if (low == k - 1)
            flag = 0;
        else {
            if (low < k - 1) {
                low0 = ++low;
                high = high0;
            }
            else {
                high0 = --high;
                low = low0;
            }
        }
    }
    for (i = 0; i < k; i++)
        s1 += A[i];
    for (i = k; i < n; i++)
        s2 += A[i];
    return s2 - s1;
}
typedef enum{RED,WHITE,BLUE} color;
void Flag_Arrange(color A[], int n) {
    int i = 0, j = 0, k = n - 1;
    while(j<=k)
        switch (A[j]) {
        case RED:
            swap(A[i], A[j]);
            i++;
            j++;
            break;
        case WHITE:
            j++;
            break;
        case BLUE:swap(a[j], a[k]);
            k--;
        }
}