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HDU 5166 Missing number 简单数论

Missing number

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)

Problem Description

There is a permutation without two numbers in it, and now you know what numbers the permutation has. Please find the two numbers it lose.

Input

There is a number T shows there are T test cases below. (T≤10)
For each test case , the first line contains a integers n , which means the number of numbers the permutation has. In following a line , there are n distinct postive integers.(1≤n≤1,000)

Output

For each case output two numbers , small number first.

Sample Input

2
3
3 4 5
1
1

Sample Output

1 2
2 3

题意

找出一个数列中缺的两个数。

分析

本来没啥好说的,记录完了之后O(n)扫描一遍即可,启发就是一种简单的O(1)的算法也要多多注意下。

1
2
Sum(n)    =n*(n+1)/2
Sum(n^2) =n*(n+1)*(2n+1)/6