Submission #1304100

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

const int MAX_N = 1000;
int R[ MAX_N + 5 ];
const long double pi = (long double) 3.14159265358979;

int main( int argc, char *argv[] )
{
int i;
int N;
long long iSum;

	ios::sync_with_stdio( false );
	cin.tie( 0 );

	cin >> N;
	for( i = 0; i < N; i++ ) cin >> R[ i ];

	sort( R, R + N );

	iSum = 0;
	for( i = 0; i < N; i++ )
	{
		if( ( N - i ) % 2 == 1 )
			iSum += R[ i ] * R[ i ];
		else
			iSum -= R[ i ] * R[ i ];
	}

	cout << fixed << setw( 10 ) << pi * iSum << endl;

	return 0;
}

Submission Info

Judge Result