[UVa]10929:You can say 11

1.此題數字過大，需用字串存取，
轉成數值必須經過ASCII碼的換算。

2.判斷11的倍數：偶數位和與奇數位和之差需要是11的倍數。

3.判斷N是否為0，必須判斷N[0]=='0'和N[1]=='\0'，不然會WA。

[C](0.016)

	#include<stdio.h>
	#include<string.h>
	#include<math.h>
	int main()
	{
	char N[1005];
	while( gets(N) && !(N[0] == '0' && N[1] == '\0') )
	{
	int odd = 0, even = 0, i;
	int N_length = strlen(N);
	for( i = 0 ; i < N_length ; i++ )
	if( i % 2 )
	odd += N[i] - '0';
	else
	even += N[i] - '0';
	if( !(abs(odd - even) % 11 ) )
	printf( "%s is a multiple of 11.\n", N );
	else
	printf( "%s is not a multiple of 11.\n", N );
	}
	return 0;
	}

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