算法导论chapter2-2.1 Insertion sort

2.1 Insertion sort

Insertion Sort

#include <iostream>
using namespace std;

int main()
{
    int a[]={5,2,4,6,1,3};
    int n=5;
    
    for (int j=1;j<=n;++j)
    {
        int key=a[j];
        int i=j-1;
        while (( i >= 0)&& (a[i]>key))
        {
            a[i+1]=a[i];
            --i;
        }
        a[i+1]=key;
    }
    
    for (int k=0;k<=5;++k)
        cout<<a[k]<<endl;

    return 0;
}

Exercise 2.1-2

Rewrite the INSERTION-SORT procedure to sort into nonincreasing instead of nondecreasing order.

#include <iostream>
using namespace std;

int main()
{
    int a[]={5,2,4,6,1,3};
    int n=5;

for (int j=1;j<=n;++j)
    {
        int key=a[j];
        int i=j-1;
        while (( i >= 0)&& (a[i]<key))
        {
            a[i+1]=a[i];
            --i;
        }
        a[i+1]=key;
    }
    
    for (int k=0;k<=5;++k)
        cout<<a[k]<<endl;

    return 0;
}

Exercise 2.1-3

Linear Search

/*
***************************************************************************************
Linear search
Input: A sequence of n numbers A=<a1,a2,...,an> and a value v.
Output: An index i such that v=A[i] or the special value NIL if v does not appear in A.
***************************************************************************************
*/

#include <iostream>
using namespace std;

int main()
{
    int a[]={5,2,4,6,1,3};
    int n=5;
    int v;
    cout<<"Please Enter a number: "<< endl;
    cin>>v;

    for (int i=0;i<=n;++i)
    {
        if (a[i]==v)
            cout<<"V=A["<<i+1<<"]"<<endl;
        else 
            cout<<" "<<endl;
    }
    return 0;
}