不用排序，c/c++找第k小元素代码
编译环境vs2013，源代码如下：

#include<iostream>
using namespace std;
void Sort(int k,int a[],int start,int end)
{
    int s = a[start];
    int t=start;
    int m = 0;
    for (int i = start+1; i < end+1; i++)
    {
        if (s > a[i])
        {
            t++;
            if (i != t)
            {
                m = a[i];
                a[i] = a[t];
                a[t] = m;
            }
        }
    }
    a[start] = a[t];
    a[t] = s;

    //cout << t << " ";
    if (t == k-1)
    {
        //cout << endl;
        cout << s<<endl;
    }
    else if (t > k-1)
    {
        Sort(k, a, start, t-1);
    }
    else
    {
        Sort(k, a, t+1, end);
    }
}
int main()
{
    int N,K,a[100];
    cout << "请输入N" << endl;
    cin >> N;
    for (int i = 0; i < N; i++)
    {
        cin >> a[i];
    }
    cout << "请输入K" << endl;
    cin >> K;
    Sort(K,a,0,N-1);
    system("pause");
    return 0;
}