题解 | #寻找第K大#

 * 
 * @param a int整型一维数组 
 * @param aLen int a数组长度
 * @param n int整型 
 * @param K int整型 
 * @return int整型
 *
 * C语言声明定义全局变量请加上static，防止重复定义
 */
int partition(int* a, int low, int high){
    int p = a[low];
    while(low < high){
        while(low < high && a[high] <= p)high--;
        a[low] = a[high];
        while(low < high && a[low] >= p)low++;
        a[high] = a[low];
    }
    a[low] = p;
    return low;
}
int quicksort(int* a, int low, int high, int K){
    int p;
    if(low < high){
        p = partition(a, low, high);
        if(p == K){
            return p;
        }else if(p < K){
            quicksort(a, p+1, high, K);
        }else{
            quicksort(a, low, p-1, K);
        }
    }
    return p;
}
int findKth(int* a, int aLen, int n, int K ) {
    // write code here
    quicksort(a, 0, aLen-1, K-1);
    return a[K-1];
}