PAT 乙级 B1048

Question

题目网址:https://pintia.cn/problem-set...

拿到冷神的代码了, 网上也有各种答案, 但是还是自己的代码, 改不对.

#define _CRT_SECURE_NO_WARNINGS 
#include <cstdio> 
#include <cstring> 
#include <algorithm>

int main(){ 
    char anum[105], bnum[105], cnum[110]; 
    char s[14] = {'0','1','2','3','4','5','6','7','8','9','J','Q','K'}; 
    scanf("%s %s", anum, bnum);
           int alen = strlen(anum) - 1;
           int blen = strlen(bnum) - 1; 
    int c, savec;
           if(alen>blen) {c=alen; savec=alen; } 
    else {c=blen; savec=blen; }
    while(alen>=0 || blen>=0 ){
        int numa = alen<0 ? 0:anum[alen]-'0';
        int numb = blen<0 ? 0:bnum[blen]-'0';
               if( c%2==1 ){ 
            int temp = numb - numa; 
            if(temp < 0) temp = temp + 10; 
            cnum[c] = temp + '0'; 
        } 
        if( c%2==0 ){ 
            cnum[c] = s[ (numb + numa)%13 ]; 
        }
            //printf("%s %d %d %d\n", cnum, alen, blen, c);    
        blen--;    alen--; c--; 
    } 
    cnum[savec+1]='\0';
    printf("%s", cnum);
    return 0;
}

各位大佬来给出出主意啊