题解 | #字符串加解密#

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

void encrypt(char* s)
{
    unsigned int length,i;

    length = strlen(s);
    for (i=0; i<length; ++i) {
        if (s[i]>='a' && s[i]<='z') {
            if (s[i] == 'z') {
                s[i] = 'A';
            } else {
                s[i] += 1+'A'-'a';
            }
        } else if (s[i]>='A' && s[i]<='Z') {
            if (s[i] == 'Z') {
                s[i] = 'a';
            } else {
                s[i] += 1+'a'-'A';
            }
        } else if (s[i]>='0' && s[i]<='9') {
            if (s[i] == '9') {
                s[i] = '0';
            } else {
                s[i] += 1;
            }
        }
    }
}

void decrypt(char* s)
{
    unsigned int length,i;

    length = strlen(s);
    for (i=0; i<length; ++i) {
        if (s[i]>='a' && s[i]<='z') {
            if (s[i] == 'a') {
                s[i] = 'Z';
            } else {
                s[i] += 'A'-'a'-1;
            }
        } else if (s[i]>='A' && s[i]<='Z') {
            if (s[i] == 'A') {
                s[i] = 'z';
            } else {
                s[i] += 'a'-'A'-1;
            }
        } else if (s[i]>='0' && s[i]<='9') {
            if (s[i] == '0') {
                s[i] = '9';
            } else {
                s[i] -= 1;
            }
        }
    }
}

int main() {
    char input[2][1001] = {};

    scanf("%s", input[0]);
    scanf("%s", input[1]);

    encrypt(input[0]);
    decrypt(input[1]);
    printf("%s\n%s", input[0], input[1]);
    
    return 0;
}