1011

class Solution {
public:
    int shipWithinDays(vector<int>& weights, int D) {
        // Sort the weights.
        int r, l, ans;
        r = accumulate(weights.begin(), weights.end(), 0);
        l = max(r/D, *max_element(weights.begin(), weights.end()));

        while(l<=r){
            int mid = (l+r)/2;
            if(canShip(weights, mid, D)){
                ans = mid;
                r = mid-1;
            }
            else{
                l = mid+1;
            }
        }
        return ans;
    }

    bool canShip(vector<int>& weights, int cap, int d){
        int days = 1, sum = 0;
        for(auto &w: weights){
            sum += w;
            if(sum > cap){
                days++;
                sum = w;
            }
        }
        return days <= d;
    }
};