[UVa]543:Goldbach's Conjecture

建質數表，從1開始找質數，看看能不能找到兩個質數加起來等於輸入值，
那麼第一組找到的即是b-a相差最大的一組，即是所求。

[C](0.060)

	#include<stdio.h>
	int prime[1000005] = { 1, 0, 0 };
	int main()
	{
	int i, j;
	for( i = 2 ; i <= 1000000 ; i++ )
	if( !prime[i] )
	for( j = i+i ; j <= 1000000 ; j+=i )
	prime[j] = 1;
	int n;
	while( scanf( "%d", &n ) != EOF && n != 0 )
	{
	int print = 0;
	for( i = 2 ; i <= n ; i++ )
	if( !prime[i] && !prime[n-i] )
	{
	printf( "%d = %d + %d\n", n, i, n-i );
	print = 1;
	break;
	}
	if( !print )
	printf( "Goldbach's conjecture is wrong.\n" );
	}
	return 0;
	}

view raw UVa543.c hosted with ❤ by GitHub