有一个整数数组，请你根据快速排序的思路，找出数组中第 k 大的数。
例如： 输入 [1,3,5,2,2], 找出数组中第2大的数，输出 3.
#include <iostream>using namespace std; #include <stack>
#include <string>
#include <queue>
#include <vector>int my_partition(std::vector<int>& a, int low, int high, int n, int k)
{int v = a[low];int i = low; int j = high;//分界点确保 i < j while(i < j){while (i < j && a[j] >= v)j--;while (i < j && a[i] <= v)i++;if(i < j)swap(a[i], a[j]); }swap(a[low], a[j]); if (n - j == k){return a[j];}else if (n - j < k){return my_partition(a, low, j-1, n, k);}else{return my_partition(a, j + 1, high, n, k);}
}int findKth(std::vector<int>& a, int n, int k)
{return my_partition(a, 0, n - 1, n, k);}int main()
{std::vector<int> data1 = { 1, 3, 5, 2, 2 };std::cout << findKth(data1, 5, 3) << std::endl;std::vector<int> data2 = { 10, 10, 9, 9, 8, 7, 5, 6, 4, 3, 4, 2 };std::cout << findKth(data2, 12, 3) << std::endl;return 0;
}
)
