HDU2673：shǎ崽 OrOrOrOrz

最新推荐文章于 2020-03-10 22:28:43 发布

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#ACM #hdu #快排 #杭电 #解题报告

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本文介绍了一道ACM竞赛中的经典题目——按特定规则选择序列中的数字，并详细展示了使用快速排序算法解决该问题的过程。通过示例输入输出，读者可以清晰地理解问题的要求及解题思路。

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Problem Description

Acmer in HDU-ACM team are ambitious, especially shǎ崽, he can spend time in Internet bar doing problems overnight. So many girls want to meet and Orz him. But Orz him is not that easy.You must solve this problem first.
The problem is :
Give you a sequence of distinct integers, choose numbers as following : first choose the biggest, then smallest, then second biggest, second smallest etc. Until all the numbers was chosen .
For example, give you 1 2 3 4 5, you should output 5 1 4 2 3

Input

There are multiple test cases, each case begins with one integer N(1 <= N <= 10000), following N distinct integers.

Output

Output a sequence of distinct integers described above.

Sample Input

5
1 2 3 4 5

Sample Output

5 1 4 2 3

快排的运用

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int cmp(const void *a,const void *b)
{
    return (*(int *)a-*(int*)b);
}

int main()
{
    int n,i,num[10005],a[10005];
    while(cin >> n)
    {
        int flag,flag2;
        flag = n/2;
        flag2 = n-flag;
        memset(a,0,sizeof(a));
        memset(num,0,sizeof(num));
        for(i = 0;i<n;i++)
        cin >> num[i];
        qsort(num,n,sizeof(int),cmp);
        int k = 0;
        for(i = n-1;flag2--;i--)
        {
            a[k] = num[i];
            k+=2;
        }
        k = 1;
        for(i = 0;flag--;i++)
        {
            a[k] = num[i];
            k+=2;
        }
        cout << a[0];
        for(i = 1;i<n;i++)
        {
            cout << " " << a[i];
        }
        cout << endl;
    }

    return 0;
}