class Solution

{

public:

    int calc_days(vector<int>& weights, int V)

    {

        int len = weights.size(), days=, i=, cur=;

        while(i<len)

        {

            if(cur+weights[i] > V)

            {

                days++;

                cur=;

            }

            cur += weights[i++];

        }

        if(cur>)

            days++;

        return days;

    }

    int shipWithinDays(vector<int>& weights, int D)

    {

        int high=, lenw=weights.size(), low=;

        for(int i=; i<lenw; i++)

        {

            high += weights[i];

            low = max(low, weights[i]);

        }

        int res=;

        while(low<=high)

        {

            int mid = (high+low)>>;

            if(D >= calc_days(weights, mid))

            {

                high = mid-;

                res = mid;

            }

            else

                low = mid+;

        }

        return res;

    }

};