ref

306c.cc

int solve(int p, int take, int num){
    int &ret = dp[p][take][num];
    if(p==n){
        if(take>0 and num==0) return ret = 1;
        return ret = 0;
    }
    if(ret!=-1) return ret;   
    int t = (num*10)+(s[p]-'0');
    //take digit at position p or not
    int a = solve(p+1, take+1, t%8);
    int b = solve(p+1, take, num);
    return ret = max(a,b);  
}