[Algorithm] Leko CCB Financial Technology Competition

Two contestants can also enter the top 100, hhh

Jianxin 01. Delete linked list nodes at intervals

Give you the head node of a linked list head, delete another node every other node (requires to keep the head node).
Please return the head node of the final linked list.

Example 1:

enter:head = [1,2,3,4]

output:[1,3]

Explanation:
The blue nodes are deleted nodes

Example 2:

enter:head = [5,1,8,6,1]

output:[5,8,1]

hint:

• The number of nodes in the linked list is [1, 5000]within range.
• 1 <= Node.val <= 10000

speed pass

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
    def deleteListNode(self, head: ListNode) -> ListNode:
        cur=head
        while cur and cur.next:
            cur.next=cur.next.next
            cur=cur.next
        return head

CCB 02. Histogram Analysis

There are N columns in a certain histogram, and the height of each column is recorded heightsin according to the sequence. Assuming that cntany number of columns can form a column group, please find the column group with the smallest difference between the maximum height and the minimum height among all possible column groups, and return the column group in ascending order of height. If there are multiple column groups that meet the condition, return the column group with the smallest element.

Example 1:

enter:heights = [3,2,7,6,1,8], cnt = 3

output:[1,2,3]

Explanation: [1,2,3] and [6,7,8] all meet the condition that the difference between the maximum height and the minimum height is the smallest in all column groups, and the first element with the smallest [1, 2,3] returns.

Example 2:

enter:heights = [4,6,1,8,4,10], cnt = 4

output:[4,4,6,8]

Explanation: The column group [4,4,6,8] satisfies the condition that the difference between the maximum height and the minimum height is the minimum.

hint:

• 2 <= cnt < heights.length <= 10^5
• 0 <= heights[i] <= 10^6

Fixed-length sliding window, easy

class Solution:
    def analysisHistogram(self, heights: List[int], cnt: int) -> List[int]:
        heights.sort()
        n=len(heights)
        i,j=0,cnt-1
        res=(0,float('inf'))
        while j<n:
            tmp=heights[j]-heights[i]
            if res[1]>tmp:
                res=(i,tmp)
            i+=1
            j+=1
        idx=res[0]
        return heights[idx:idx+cnt]