2190.txt

北大ACM题目例程 详细的解答过程 程序实现 算法分析

#include <iostream.h>
#include <stdio.h>

char w[20];

int main()
{
	int i,s,t,j;
	cin>>w;

	t = 10; s = 0;

	for( i=0; w[i]!='\0' ; i++, t-- )
	if( w[i] != '?' )
	{
		if( w[i] != 'X' )
			s += t * ( w[i] - '0' );
		else s += t * 10;
	}
	else j=t;

	for( i=0; i<10; i++ )
		if( (j*i+s)%11 == 0 )
			break;

	if( i == 10 )
	{
		if( j == 1 && (j*i+s)%11 == 0 )
		{
			printf( "X\n" );
		}
		else printf( "-1\n" );
	}
	else printf( "%d\n", i );

	return 0;
}