力扣---2020.5.1

21. 合併兩個有序鏈表

class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode dummyHead = new ListNode(-1);
        ListNode curr = dummyHead;
        while(l1!=null && l2!=null){
            if(l1.val<l2.val){
                curr.next = l1;
                curr = curr.next;
                l1 = l1.next;
            }else{
                curr.next = l2;
                curr = curr.next;
                l2 = l2.next;
            }
        }
        if(l1==null){
            curr.next = l2;
        }
        if(l2==null){
            curr.next = l1;
        }
        return dummyHead.next;
    }
}

class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if(l1==null){
            return l2;
        }
        if(l2==null){
            return l1;
        }
        if(l1.val<=l2.val){
            l1.next = mergeTwoLists(l1.next,l2);
            return l1;
        }else{
            l2.next = mergeTwoLists(l1,l2.next);
            return l2;
        }
    }
}

面試題14- II. 剪繩子 II

class Solution {
    public int cuttingRope(int n) {
        if(n == 2)
            return 1;
        if(n == 3)
            return 2;
        long res = 1;
        while(n > 4){
            res *= 3;
            res = res % 1000000007;
            n -= 3;
        }
        return (int)(res * n % 1000000007);
    }
}

你知道的越多，你不知道的越多。