//
//  main.cpp
//findk
//
//  Created by Xiao Bang on 2017/6/28.
//  Copyright © 2017年 Xiao Bang. All rights reserved.
//
#include <vector>
#include <iostream>
using namespace std;


template <typename Comparable>
const Comparable & median3(vector<Comparable> & a, int left, int right){
    int center = (left + right) / 2;
    if(a[center] < a[left])
        swap(a[center],a[left]);
    if(a[right] < a[left])
        swap(a[right],a[left]);
    if (a[right] < a[center])
        swap(a[right],a[center]);
    
    swap(a[center],a[right - 1]);
    return a[right - 1];
    
}


template <typename Comparable>
Comparable  partion( vector<Comparable> & a, int left, int right){
    
    const Comparable & pivot = median3(a,left,right);
    int i = left;
    int j = right - 1;
    for (;;) {
        while(a[++i] < pivot) {}
        while(pivot < a[--j]) {}
        if (i < j)
            swap(a[i],a[j]);
        else break;
    }
    
    swap (a[i],a[right - 1]);
    return i;
}
template <typename Comparable>
Comparable findK(vector<Comparable> & a,int k) {
    int nk =k -1;
    int left = 0;
    int right = (int)(a.size()-1);
    int index = partion(a,left,right);
    while(index != nk) {
        if (nk < index)
            index = partion(a,left, index -1);
        else
            index = partion(a,index+1,right);
    }
    return a[nk];
}



int main(int argc, const char * argv[]) {
    vector <int> array1 {1,2,4,6,7,8,1,0,1,14,12,16,44,66,34,72,3,8,4,9,0,14};
    // vector <int> array1 {1,2,4,6,7,8,1,0,1,14,12,14,12,16,44,66,34,72};
    int b= findK(array1,10);
    
    cout << b << '\t';
}