【leetcode】67. 二进制求和

#define MAXLEN 10001
char * addBinary(char * a, char * b){
    char* arr=(char*)calloc(MAXLEN+1,sizeof(char));
    int right1=strlen(a)-1, right2=strlen(b)-1, flag=0, i, pst=MAXLEN, temp1, temp2;
    while(right1>=0 || right2>=0 || flag){
        temp1=(right1>=0)?a[right1--] :'0';
        temp2=(right2>=0)?b[right2--] :'0';
        arr[--pst]='0'+(temp1-'0'+temp2-'0'+flag)%2;
        flag=(temp1-'0'+temp2-'0'+flag >= 2)?1 :0;
    }
    return arr+pst;
}