2126.txt

北大ACM题目例程 详细的解答过程 程序实现 算法分析

import java.util.*;
import java.io.*;

public class Main {
	static public void main( String [] s ) throws Exception{
		Scanner cin = new Scanner(System.in);
		int n;
		int a[];
		
		n = cin.nextInt();
		a = new int[n+1];
		for( int i=0; i<=n; i++ )
			a[i] = cin.nextInt();
		
		if( n > 2 )
			System.out.println( "NO" );
		else if( n <= 1 )
			System.out.println( "YES" );
		else {
			if( a[1]*a[1]-4*a[0]*a[2] >=0 )
				System.out.println( "NO" );
			else
				System.out.println( "YES" );
		}
		
		return;
	}
}