4.7 練手

Leetcode 21. Merge Two Sorted Lists

 

一开始解决方式（特别慢，特别乱： beat 10%+ 我个菜

class Solution(object):
    def mergeTwoLists(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        if l1 == None:
            return l2
        if l2 == None:
            return l1
        k = ListNode(0)
        if l1.val <= l2.val:
            keepList = l1
            aList = l2
            k.next = l1
        else:
            keepList = l2
            aList = l1
            k.next = l2
        
        while aList:
            indexVal = keepList.val
            #print(indexVal)
            #print(aList.val)
            if (aList.val >= indexVal):
                if(keepList.next == None):
                    keepList.next = aList
                    break
                else:
                    if(keepList.next.val > aList.val):
                        if(aList.next == None or aList.next.val >= keepList.next.val):
                            temp = aList.next
                            aList.next = keepList.next
                            keepList.next = aList
                            aList = temp
                            keepList = keepList.next.next
                        else:
                            temp = keepList.next
                            keepList.next = aList
                            keepList =  keepList.next.next
                            aList = temp
                            
                    else:
                        keepList = keepList.next
        return k.next

 

第二次： 60% + 就是运行时间不知道为什么比较玄学，代码如下：

class Solution(object):
    def mergeTwoLists(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        if l1 == None:
            return l2
        if l2 == None:
            return l1
        root = ListNode(0)
        cur = root
        while l1 and l2:
            if(l1.val <= l2.val):
                cur.next = ListNode(l1.val)
                l1 = l1.next
            else:
                cur.next = ListNode(l2.val)
                l2 = l2.next
            cur = cur.next
        if l1:
            cur.next = l1
        if l2:
            cur.next = l2
        return root.next

 

决定看Discuss:

解法1. 也不太快的递归解法：（但是就是很神奇 Genius!

class Solution(object):
    def mergeTwoLists(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        if not l1:
            return l2
        elif not l2:
            return l1
        elif l1.val < l2.val:
            l1.next = self.mergeTwoLists(l1.next, l2) 
            return l1
        else:
            l2.next = self.mergeTwoLists(l1, l2.next)
            return l2

 

well.好像其他解法也不太快的样子，可能是python语言本身的问题？（逃...