hdoj 2100 Lovekey 【另类A+B】

#include <stdio.h>
#include <string.h>
#define M 210
char a[M], b[M],c[M];
int main(){
    while(scanf("%s%s", a, b) == 2){
        int la = strlen(a)-1;
        int lb = strlen(b)-1;
        memset(c, 0, sizeof(c));
        int k = 0;
        while(la>=0&&lb>=0){
            c[k] = a[la]+(b[lb]-'A');
            la--; lb --; k++;
        }
        while(la>=0){
            c[k++] = a[la]; la--;
        }
        while(lb >= 0){
            c[k++] = b[lb]; lb --;
        }
        //printf("..");
        int i = 0;
        while(i < k){
            if(c[i]>'Z'){
                c[i] -= 26;
                c[i+1] += 1;
            }
            i++;
        }
        if(c[k]){
            c[k++] += 'A';
        }
        while(c[k-1] == 'A'&&k > 0) k --;
        for(i = k-1; i > 0; i --)
            printf("%c", c[i]);
        printf("%c\n", c[0]);
    }
}