值得用一首歌时间来阅读的文章

One Song,One Article!

We have already learned how to use the algorithm of quick_sort ,however ,when we want to complete something else,we need and have to turn back and rewrite the code again. Therefore, be familiar with the quick_sort's main thought and be skilled with coding are vital to everyone especially you who are programmer. So, I just want to give the code of quick_sort for you and me.

Do you want some changes?

Or just use the sort(A),sort(B),sort(blablabla);

Here I give the code which comes from the famous book---Introduction to algorithm.

Enjoy it with the background music!

#include <bits/stdc++.h>
#define max_size 100010
int A[max_size];

using namespace std;
int PARTITION(int A[],int p,int r)
{
    int x=A[r];
    int i=p-1;
    for(int j=p; j<=r-1; j++)
    {
        if(A[j]<=x)
        {
            i++;
            swap(A[i],A[j]);
        }
    }
    swap(A[i+1],A[r]);
    return i+1;
}

int RANDOMIZED_PARTITION(int A[],int p,int r)
{
    int i=rand()%(r-p+1)+p;
    swap(A[r],A[i]);
    return PARTITION(A,p,r);
}
void RANDOMIZED_QUICKSORT(int A[],int p,int r)
{
    if(p<r)
    {
        int q=RANDOMIZED_PARTITION(A,p,r);
        RANDOMIZED_QUICKSORT(A,p,q-1);
        RANDOMIZED_QUICKSORT(A,q+1,r);
    }
}

int RANDOMIZED_SELECT(int A[],int p,int r,int i)
{
    if(p==r)
    {
        return A[p];
    }
    int q=RANDOMIZED_PARTITION(A,p,r);
    int k=q-p+1;
    if(i==k) return A[q];
    else if(i<k)
        return RANDOMIZED_SELECT(A,p,q-1,i);
    else return RANDOMIZED_SELECT(A,q+1,r,i-k);
}

int main()//快排程序加第i顺序统计量
{
    int n;
    cout<<"请输入数组长度:"<<endl;
    while(~scanf("%d",&n))
    {
        memset(A,0,sizeof(A));
        for(int i=1; i<=n; i++)
        {
            scanf("%d",&A[i]);
        }
        cout<<"快排结果:"<<endl;
        RANDOMIZED_QUICKSORT(A,1,n);
        for(int i=1; i<=n; i++)
        {
            cout<<A[i]<<" ";
        }
        int t;
        cout<<"\n请输入查询次数"<<endl;
        cin>>t;
        while(t--)
        {
            int key;
            cout<<"请输入查找第i小的数"<<endl;
            cin>>key;
            int result=RANDOMIZED_SELECT(A,1,n,key);
            cout<<"第"<<key<<"小的数是:"<<result<<endl;
        }
    }
    cout<<"Program over!"<<endl;
    return 0;
}

I just learn how to add background music, there are still many bugs which are waiting to debug! Choose enjoy it or you can just turn off it.