题目描述：

LeetCode 725. Split Linked List in Parts

Given a (singly) linked list with head node root, write a function to split the linked list into k consecutive linked list "parts".

The length of each part should be as equal as possible: no two parts should have a size differing by more than 1. This may lead to some parts being null.

The parts should be in order of occurrence in the input list, and parts occurring earlier should always have a size greater than or equal parts occurring later.

Return a List of ListNode's representing the linked list parts that are formed.

Examples 1->2->3->4, k = 5 // 5 equal parts [ [1], [2], [3], [4], null ]

Example 1:

Input: 
root = [1, 2, 3], k = 5
Output: [[1],[2],[3],[],[]]
Explanation:
The input and each element of the output are ListNodes, not arrays.
For example, the input root has root.val = 1, root.next.val = 2, \root.next.next.val = 3, and root.next.next.next = null.
The first element output[0] has output[0].val = 1, output[0].next = null.
The last element output[4] is null, but it's string representation as a ListNode is [].

Example 2:

Input: 
root = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], k = 3
Output: [[1, 2, 3, 4], [5, 6, 7], [8, 9, 10]]
Explanation:
The input has been split into consecutive parts with size difference at most 1, and earlier parts are a larger size than the later parts.

Note:

• The length of root will be in the range [0, 1000].
• Each value of a node in the input will be an integer in the range [0, 999].
• k will be an integer in the range [1, 50].

题目大意：

将链表拆分成长度之差不大于1的k个片段。

解题思路：

首先求链表长度s

利用除数和余数将整数s划分为长度之差不大于1的k个整数，参考：Python实现整数均分

然后遍历链表进行拆分

Python代码：

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def splitNum(self, m, n):
        q, r = m / n, m % n
        if r > 0: return [q + 1] * r + [q] * (n - r)
        if r < 0: return [q] * (n + r) + [q - 1] * -r
        return  [q] * n

    def listLength(self, root):
        ans = 0
        while root:
            ans += 1
            root = root.next
        return ans

    def splitListToParts(self, root, k):
        """
        :type root: ListNode
        :type k: int
        :rtype: List[ListNode]
        """
        ans = []
        s = self.listLength(root)
        for p in self.splitNum(s, k):
            if not p:
                ans.append(None)
                continue
            node = root
            for x in range(p - 1):
                node = node.next
            ans.append(root)
            root = node.next
            node.next = None
        return ans

 

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