题解 | #字符串加密#

#include <stdio.h>
#include <string.h>

static char WordTable[26];
static char newWordTable[26];

char large(char temp)
{
    return temp>'Z'?temp-32:temp;
}

void rebuildkey(char* key, int length,char* newkey, int* newkeylen)
{
    int hashT[26] = {0};
    for(int i = 0; i< length;i++)
    {
        char temp = large(key[i]);
        hashT[temp-'A']++;
    }
    //重构word table
    int k = 0;
    for(int i=0;i<length;i++)
    {

            char temp = large(key[i]);
            if(hashT[temp-'A'])
            {
                newkey[k++] = temp;
                hashT[temp-'A'] = 0;
                
           }
            
    }
    *newkeylen = k;
}

int wordinkey(char word, char* key, int len)
{
    for(int i=0;i<len;i++)
    {
        if(word ==key[i])
        {
            return 1;
        }
    }
    return 0;
}


void rebuildwordtable(char* oldwordtable, char* newwordtable,char* newkey,int newkeylen)
{
    int i =0;
    for(;i<newkeylen;i++)
    {
        newwordtable[i] = newkey[i];
    }

    for(int j =0;j<26;j++)
    {
        if(!wordinkey(oldwordtable[j],newkey,newkeylen))
        {
            newwordtable[i++] = oldwordtable[j];
        }
    }
}

int main() {
    char key[100];
    char str[100];
    char newkey[100];
    scanf("%s\n",key);
    scanf("%s\n",str);
    WordTable[0] = 'A';
    for(int i=1;i<26;i++)
    {
        WordTable[i] = WordTable[i-1]+1;
    }
    int length = strlen(key);
    int newlen = 0;

    rebuildkey(key,length, newkey, &newlen);

    rebuildwordtable(WordTable, newWordTable, newkey, newlen);

    for(int i = 0;i<strlen(str);i++)
    {
        int index = large(str[i])-'A';
        if(str[i]<'a')
        {
            printf("%c",newWordTable[index]);//大写
        }
        else {
            printf("%c",(newWordTable[index])+32);//小写
        }
        
    }

    return 0;
}