Method BinarySearch

java/2251-number-of-flowers-in-full-bloom.java:24–36

(List<Integer> ls, int target)

    }

    private int BinarySearch(List<Integer> ls, int target){
        int l = 0;
        int r = ls.size();

        while(l < r){
            int m = l + (r-l)/2;
            if(target < ls.get(m))
                r = m;
            else
                l = m + 1;    
        }
        return l;
    }
}