Foreign Exchange, foreignexchange

Foreign Exchange, foreignexchange
10763 Foreign Exchange
Your non-profit organization (iCORE-international Confederation of Revolver Enthusiasts) coordinates
A very successful foreign student exchange program. Over the last few years, demand has
Sky-rocketed and now you need maintenance ance with your task.
The program your organization runs works as follows: All candidates are asked for their original
Location and the location they wowould like to go to. The program works out only if every student has
Suitable exchange partner. In other words, if a student wants to go from A to B, there must be another
Student who wants to go from B to A. This was an easy task when there were only about 50 candidates,
However now there are up to 500000 candidates!
Input
The input file contains multiple cases. Each test case will consist of a line containing n-the number
Of candidates (1≤n ≤ 500000), followed by n lines representing the exchange information for each
Candidate. Each of these lines will contain 2 integers, separated by a single space, representing
Candidate's original location and the candidate's target location respectively. Locations will be represented
By nonnegative integer numbers. You may assume that no candidate will have his or her original
Location being the same as his or her target location as this woshould fall into the domestic exchange
Program. The input is terminated by a case where n = 0; this case shocould not be processed.
Output
For each test case, print 'yes' on a single line if there is a way for the exchange program to work out,
Otherwise print 'no '.
Sample Input
10
1 2
2 1
3 4
4 3
100 200
200 100
57 2
2 57
1 2
2 1
10
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
0
Sample Output
YES
NO question: Just judge YES. If YES, the contents of the two arrays are the same for the locations of all characters and all destinations, but the positions are different, so you only need to sort them in the descending order. Then, the two arrays are subtracted from each other at the same position. When the value is not equal to 0, the output is NO. Otherwise, the "YES" code is as follows: (I am a little white. If you have a word, I hope you can understand it)

# Include <iostream>
# Include <algorithm>
Using namespace std;
Int a [500000], B [500000];
Int main ()
{
Int n;
While (cin> n & n)
{

For (int I = 0; I <n; I ++)
Cin> a [I]> B [I];
Int f = 1;
Sort (a, a + n );
Sort (B, B + n );
For (int I = 0; I <n; I ++)
{
If (a [I]! = B [I])
{
F = 0;
Break;
}
}
// Cout <f <endl;
If (f)
Cout <"YES" <endl;
Else
Cout <"NO" <endl;
}
Return 0;

}