？？？为什么我只有60分？？？

#include<bits/stdc++.h>
using namespace std;
char sa[1010],sb[1010];
int la,lb,lc,a[1010],b[1010],c[1010];
int main(){
    scanf("%s",sa);
    scanf("%s",sb);
    la = strlen(sa);
    lb = strlen(sb);
    memset(a,0,sizeof(a));
    memset(b,0,sizeof(b));
    for(int i = 0; i < la; i++)
        a[la-i-1] = sa[i] - '0';
    for(int i = 0; i < lb; i++)
        b[lb-i-1] = sb[i] - '0';
    lc = la > lb ? la : lb;
    memset(c,0,sizeof(c));
    for(int i = 0; i < lc; i++){
        c[i] = a[i] + b[i] +c[i];
        if(c[i] >= 10){
            c[i+1] = 1;
            c[i] -= 10;
        }
    }
    if(c[lc] > 0) lc++;
    for(int i = lc - 1; i >= 0; i--)
    printf("%d",c[i]);
    return 0;
}