题解 | #简单密码#

#include <stdio.h>

int isNum(char ch)
{
    if(ch >= '0' && ch <= '9')
        return 1;
    return 0;
}

int isBigAlpha(char ch)
{
    if(ch >= 'A' && ch <= 'Z')
        return 1;
    return 0;
}

int isSmallAlpha(char ch)
{
    if(ch >= 'a' && ch <= 'z')
        return 1;
    return 0;
}

char changeBigAlpha(char ch)
{
    ch = ch - 'A' + 'a' + 1;
    if(ch == 'z' + 1)
        ch = 'a';
    return ch;
}
char getSmallAlpha(char ch)
{
    switch(ch)
    {
        case 'a':
        case 'b':
        case 'c':
            return '2';
        case 'd':
        case 'e':
        case 'f':
            return '3';
        case 'g':
        case 'h':
        case 'i':return '4';
        case 'j':
        case 'k':
        case 'l':return '5';
        case 'm':
        case 'n':
        case 'o':return '6';
        case 'p':
        case 'q':
        case 'r':
        case 's':return '7';
        case 't':
        case 'u':
        case 'v':return '8';
        case 'w':
        case 'x':
        case 'y':
        case 'z':return '9';
    }
    return 0;
}
int main() {
    char ch;
    char c;
    while(EOF != (ch = getchar()))
    {
        if(isBigAlpha(ch))
            c = changeBigAlpha(ch);
        else if(isSmallAlpha(ch))
            c = getSmallAlpha(ch);
        else
            c = ch;
    printf("%c",c);
    }
    return 0;
}