Time Limit: 1000MS Memory Limit: 30000K
Total Submissions: 3153 Accepted: 1414
Description
Transmitting and memorizing information is a task that requires different coding systems for the best use of the available space. A well known system is that one where a number is associated to a character sequence. It is considered that the words are made only of small characters of the English alphabet a,b,c, ..., z (26 characters). From all these words we consider only those whose letters are in lexigraphical order (each character is smaller than the next character).
The coding system works like this:
• The words are arranged in the increasing order of their length.
• The words with the same length are arranged in lexicographical order (the order from the dictionary).
• We codify these words by their numbering, starting with a, as follows:
a - 1
b - 2
...
z - 26
ab - 27
...
az - 51
bc - 52
...
vwxyz - 83681
...
Specify for a given word if it can be codified according to this coding system. For the affirmative case specify its code.
Input
The only line contains a word. There are some constraints:
• The word is maximum 10 letters length
• The English alphabet has 26 characters.
Output
The output will contain the code of the given word, or 0 if the word can not be codified.
Sample Input
bf
Sample Output
55
Source
Romania OI 2002
//
#include < iostream >
using namespace std;
static int C[ 30 ][ 30 ];
int main( int argc, char * argv[])
{
char word[ 15 ];
scanf( " %s " , word);
int len = strlen(word);
for ( int i = 1 ; i < len; ++ i)
if (word[i - 1 ] >= word[i])
{
cout << 0 << endl;
return 0 ;
};
C[ 0 ][ 0 ] = 1 ;
for ( int i = 1 ; i < 30 ; ++ i)
for ( int j = 0 ; j <= i; ++ j)
C[i][j] = (j == 0 ) ? C[i - 1 ][j] : C[i - 1 ][j - 1 ] + C[i - 1 ][j];
unsigned long long code = 0 ;
for ( int i = 1 ; i < len; ++ i) code += C[ 26 ][i];
for ( int i = 0 ; i < len; ++ i)
{
char c = (i == 0 ) ? ' a ' : word[i - 1 ] + 1 ;
for (; c <= word[i] - 1 ; ++ c)
code += C[ ' z ' - c][len - 1 - i];
}
++ code;
cout << code << endl;
return 0 ;
}
转载于:https://www.cnblogs.com/asuran/archive/2009/10/16/1584249.html