LZ78 的算法描述：
for (;;)
{
current_match = 1;
current_length = 0;
memset(test_string, '\0', MAX_STRING);
for (;;)
{
test_string[current_length ++] = getc(input);
new_match = find_match(test_string);
if (new_match) == -1)
break;
current_match = new_match;
}
output_code(current_match);
output_char(test_string[current_letgth - 1];
add_string_to_dictionary(test_string);
}
LZ78 示例：
输入正文： "DAD DADA DADDY DADO..."
输出短语 输出字符 编码后的串
0 'D' "D"
0 'A' "A"
1 ' ' "D"
1 'A' "DA"
4 ' ' "DA "
4 'D' "DAD"
1 'Y' "DY"
0 ' ' " "
6 'O' "DADO"
此时字典的情况：
0 ""
1 "D"
2 "A"
3 "D "
4 "DA"
5 "DA "
6 "DAD"
7 "DY"
8 " "
9 "DADO"
