HDU-2020 Absolute Sort_hdu - 2020 sort-优快云博客

本文链接：https://blog.youkuaiyun.com/yaoo_o/article/details/103633929

本文详细解析了一种基于绝对值的排序算法，该算法首先将输入的整数转换为正数并进行排序，然后根据原始数值的正负性恢复排序后的结果。适用于处理包含正负数的整数集合，确保了排序后的列表中元素的绝对值递增。

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See the article on https://dyingdown.github.io/2019/12/20/HDU-2020%20Absolute-Sort/

Absolute Sort

Input n (n <= 100) integers, and output them after sorting according to the absolute value. The title guarantees that for each test case, the absolute values of all numbers are not equal.

Input

There are multiple groups of input data. Each group occupies one line. The first number of each line is n, followed by n integers. N = 0 means the end of the input data. No processing is performed.

Output

For each test instance, the sorted results are output, separated by a space between the two numbers. One line per test instance.

Sample Input

3 3 -4 2
4 0 1 2 -3
0

Sample Output

-4 3 2
-3 2 1 0

Analysis

Turn then into positive numbers and sort. And for each unit in array, if it’s negative originally, turn it back to negative.

Code

#include<bits/stdc++.h>

using namespace std;

map<int,int> a;
int arr[1000];
int main() {
	int n;
	while(cin >> n, n){
		for(int i = 0; i < n; i ++) {
			cin >> arr[i];
			if(arr[i] >= 0) a[abs(arr[i])] = 0;
			else a[abs(arr[i])] = 1;
			arr[i] = abs(arr[i]);
		}
		sort(arr, arr + n, greater<int>());
		for(int i = 0; i < n; i ++) {
			if(a[arr[i]]) cout << '-' << arr[i];
			else cout << arr[i];
			if(i != n - 1) cout << " ";
			else cout << endl;
		}
	}
	return 0;
}