鍚堝苟鐨勮壓鏈?.0锛氬悎骞堕摼琛ㄣ€佹暟缁勩€佷簩鍙夋爲

Posted 2021-04-09 BU绉戠爺閫?/a> 鍚堝苟

鐩綍

1 鍚堝苟K涓湁搴忛摼琛?(鍏?

2 鍚堝苟鏈夊簭鏁扮粍

3 鍚堝苟浜屽弶鏍?/span>

1 鍚堝苟K涓湁搴忛摼琛?/span>

濂戒簡锛岄偅鐜板湪璇蜂綘灏嗗涓摼琛ㄥ悎骞跺埌涓€涓崌搴忛摼琛ㄤ腑锛岃繑鍥炲悎骞跺悗鐨勯摼琛?/span>

绀轰緥1锛?/span>

杈撳叆锛歭ists = [[1,4,5],[1,3,4],[2,6]]

杈撳嚭锛歔1,1,2,3,4,4,5,6]

  1->4->5,

  1->3->4,

  2->6

        馃憞

1->1->2->3->4->4->5->6

绀轰緥2锛?/span>

杈撳叆锛歭ists = [] 鎴?[[]]

杈撳嚭锛歔]

1.1 鍥為【涓婄瘒鏂囩珷鏂规硶鈥斺€斿垎娌?/span>

class Solution:
    def mergeKLists(self, lists: List[ListNode]) -> ListNode:
        return self.merge(lists, 0, len(lists) - 1)

    def merge(self, lists, left, right):
        # 鍒嗘不锛氬綊骞剁殑鎬濊矾
        if left == right:
            return lists[left]
        elif left > right:
            return None
        else:
            mid = (left + right) // 2
            return self.mergeTwoLists(self.merge(lists, left, mid), self.merge(lists, mid + 1, right))

    def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
        # 鏈€灏忓瓙闂锛氬悎骞?涓摼琛?/span>
        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

1.2 鍚堝苟鍚庢帓搴?/span>

class ListNode:
     def __init__(self, val=0, next=None):
         self.val = val
         self.next = next

class Solution:
    def mergeKLists(self, lists):
        nums = []
        for node in lists:
            while node: # 鐩存帴鐢╳hile node灏卞彲浠?/span>
                nums.append(node.val)
                node = node.next
        nums.sort()
        p = head = ListNode(0) # 铏氭嫙澶磋妭鐐?/span>
        for value in nums:
            p.next = ListNode(value) # 鍥哄畾娴佺▼
            p = p.next
        return head.next

2 鍚堝苟鏈夊簭鏁扮粍

鍚堝苟鏈夊簭鏁扮粍A鍜孊锛屽厓绱犱釜鏁板垎鍒负m锛宯

2.1 涓€琛屾悶瀹?/span>

class Solution:
    def merge(self, A, m, B, n):
        A[:] = sorted(A[:m]+B2)

2.2 璁剧疆鍝ㄥ叺锛?span class="mq-167"> Infinity鈥斺€?nbsp;鈭?/span>

class Solution:
    def merge(self, A, m, B, n):
        A_copy = A[:m]
        A[:] = []
        A_copy.append(float('inf'))
        B.append(float('inf'))
        i = j = 0
        for k in range(m + n):
            if A_copy[i] < B[j]:
                A.append(A_copy[i])
                i += 1
            else:
                A.append(B[j])
                j += 1

3 鍚堝苟浜屽弶鏍?/span>

鍚堝苟涓轰竴涓柊鐨勪簩鍙夋爲銆傚悎骞剁殑瑙勫垯鏄鏋滀袱涓妭鐐归噸鍙狅紝閭ｄ箞灏嗕粬浠殑鍊肩浉鍔犱綔涓鸿妭鐐瑰悎骞跺悗鐨勬柊鍊硷紝鍚﹀垯涓嶄负 NULL 鐨勮妭鐐瑰皢鐩存帴浣滀负鏂颁簩鍙夋爲鐨勮妭鐐广€?/span>绀轰緥锛?/span>

3.1 娣卞害浼樺厛鎼滅储锛?/span>

# Definition for a binary tree node.
class TreeNode:
     def __init__(self, x):
         self.val = x
         self.left = None
         self.right = None

class Solution:
    def mergeTrees(self, t1: TreeNode, t2: TreeNode) -> TreeNode:
        if not t1:
            return t2
        if not t2:
            return t1
        t = TreeNode(t1.val + t2.val)
        t.left = self.mergeTrees(t1.left, t2.left)
        t.right = self.mergeTrees(t1.right, t2.right)
        return t

3.2 骞垮害浼樺厛鎼滅储锛?/span>

鎺屾彙BFS鐨勬€濊矾鍚庯紝骞朵笉澶嶆潅

class Solution:
    def mergeTrees(self, t1: TreeNode, t2: TreeNode) -> TreeNode:
        if not t1: return t2
        if not t2: return t1
        merged = TreeNode(t1.val + t2.val)
        # deque 鏄弻杈归槦鍒楋紙double-ended queue锛夛紝鍏锋湁闃熷垪鍜屾爤鐨勬€ц川
        queue = collections.deque([merged])
        que1 = collections.deque([t1])
        que2 = collections.deque([t2])
        while que1 or que2:
            # merged姘歌繙鎸囧悜鏍癸紝node鍒欒礋璐ｉ亶鍘?/span>
            node = queue.popleft()
            node1 = que1.popleft()
            node2 = que2.popleft()
            left1, right1 = node1.left, node1.right
            left2, right2 = node2.left, node2.right
            if left1 or left2:
                if left1 and left2:
                    node.left = TreeNode(left1.val + left2.val)
                    queue.append(node.left)
                    que1.append(left1)
                    que2.append(left2)
                elif left1:
                    node.left = left1
                elif left2:
                    node.left = left2

            if right1 or right2:
                if right1 and right2:
                    node.right = TreeNode(right1.val + right2.val)
                    queue.append(node.right)
                    que1.append(right1)
                    que2.append(right2)
                elif right1:
                    node.right = right1
                elif right2:
                    node.right = right2
        return merged

Hello BU learner
娆㈣繋鍏虫敞鎴戯紝涓€璧峰涔狅紝涓€璧疯繘姝?
璺熺潃BU绉戠爺閫氾紝瀛︿範璺笂鏇磋交鏉俱€?/p>