725.SplitListToParts.cs

// 725. Split Linked List in Parts
// Given the head of a singly linked list and an integer k, 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 one. This may lead to some parts being null.
// The parts should be in the order of occurrence in the input list, and parts occurring earlier should always have a size greater than or equal to parts occurring later.
// Return an array of the k parts.

// Example 1:
// Input: head = [1,2,3], k = 5
// Output: [[1],[2],[3],[],[]]
// Explanation:
// The first element output[0] has output[0].val = 1, output[0].next = null.
// The last element output[4] is null, but its string representation as a ListNode is [].
// Example 2:
// Input: head = [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.

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     public int val;
 *     public ListNode next;
 *     public ListNode(int val=0, ListNode next=null) {
 *         this.val = val;
 *         this.next = next;
 *     }
 * }
 */
public class Solution {
    public ListNode[] SplitListToParts(ListNode head, int k) {
        int len = 0;
        ListNode curr = head;
        while(curr!=null){
            len++;
            curr = curr.next;
        }
        int arrLen = len/k;
        int mod = len % k;
        ListNode[] result = new ListNode[k];
        for(int i = 0; i < k; i++){
            result[i] = head;
            ListNode prev = head;
            int currLen = i < mod ? arrLen + 1 : arrLen;
            
            while(head != null && currLen > 0){
                prev = head;
                head = head.next;
                currLen--;
            }
            if(prev!=null)
                prev.next = null;
        }
        return result;
    }
}