[UVa]10924:Prime Words

這題就是建質數表，然後根據所給公式計算單字的值是否為質數即可。

P.S. 1在這題屬於質數。

[C](0.012)

	#include<stdio.h>
	#include<ctype.h>
	#include<string.h>
	int letter_to_i( char c )
	{
	if( isupper(c) )
	return c - 'A' + 27;
	else if( islower(c) )
	return c - 'a' + 1;
	else
	return 0;
	}
	int main()
	{
	int prime[10005] = { 1, 0, 0 };
	int i, j;
	for( i = 2 ; i <= 10000 ; i++ )
	if( !prime[i] )
	for( j = i+i ; j <= 10000 ; j+=i )
	prime[j] = 1;
	char word[25];
	while( gets(word) )
	{
	int L = strlen(word);
	int sum = 0;
	for( i = 0 ; i < L ; i++ )
	sum += letter_to_i( word[i] );
	if( prime[sum] )
	printf( "It is not a prime word.\n" );
	else
	printf( "It is a prime word.\n" );
	}
	return 0;
	}

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