{"id":8873,"date":"2021-11-28T14:10:04","date_gmt":"2021-11-28T22:10:04","guid":{"rendered":"https:\/\/zxi.mytechroad.com\/blog\/?p=8873"},"modified":"2021-11-28T19:47:47","modified_gmt":"2021-11-29T03:47:47","slug":"leetcode-160-intersection-of-two-linked-lists","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/list\/leetcode-160-intersection-of-two-linked-lists\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 160. Intersection of Two Linked Lists"},"content":{"rendered":"\n

Given the heads of two singly linked-lists headA<\/code> and headB<\/code>, return the node at which the two lists intersect<\/em>. If the two linked lists have no intersection at all, return null<\/code>.<\/p>\n\n\n\n

For example, the following two linked lists begin to intersect at node c1<\/code>:<\/p>\n\n\n\n

\"\"\/<\/figure>\n\n\n\n

The test cases are generated such that there are no cycles anywhere in the entire linked structure.<\/p>\n\n\n\n

Note<\/strong> that the linked lists must retain their original structure<\/strong> after the function returns.<\/p>\n\n\n\n

Custom Judge:<\/strong><\/p>\n\n\n\n

The inputs to the judge<\/strong> are given as follows (your program is not<\/strong> given these inputs):<\/p>\n\n\n\n

  • intersectVal<\/code> – The value of the node where the intersection occurs. This is 0<\/code> if there is no intersected node.<\/li>
  • listA<\/code> – The first linked list.<\/li>
  • listB<\/code> – The second linked list.<\/li>
  • skipA<\/code> – The number of nodes to skip ahead in listA<\/code> (starting from the head) to get to the intersected node.<\/li>
  • skipB<\/code> – The number of nodes to skip ahead in listB<\/code> (starting from the head) to get to the intersected node.<\/li><\/ul>\n\n\n\n

    The judge will then create the linked structure based on these inputs and pass the two heads, headA<\/code> and headB<\/code> to your program. If you correctly return the intersected node, then your solution will be accepted<\/strong>.<\/p>\n\n\n\n

    Example 1:<\/strong><\/p>\n\n\n\n

    \"\"\/<\/figure>\n\n\n\n
    Input:<\/strong> intersectVal = 8, listA = [4,1,8,4,5], listB = [5,6,1,8,4,5], skipA = 2, skipB = 3\nOutput:<\/strong> Intersected at '8'\nExplanation:<\/strong> The intersected node's value is 8 (note that this must not be 0 if the two lists intersect).\nFrom the head of A, it reads as [4,1,8,4,5]. From the head of B, it reads as [5,6,1,8,4,5]. There are 2 nodes before the intersected node in A; There are 3 nodes before the intersected node in B.\n<\/pre>\n\n\n\n
    Example 2:<\/strong><\/p>\n\n\n\n
    \"\"\/<\/figure>\n\n\n\n
    Input:<\/strong> intersectVal = 2, listA = [1,9,1,2,4], listB = [3,2,4], skipA = 3, skipB = 1\nOutput:<\/strong> Intersected at '2'\nExplanation:<\/strong> The intersected node's value is 2 (note that this must not be 0 if the two lists intersect).\nFrom the head of A, it reads as [1,9,1,2,4]. From the head of B, it reads as [3,2,4]. There are 3 nodes before the intersected node in A; There are 1 node before the intersected node in B.\n<\/pre>\n\n\n\n
    Example 3:<\/strong><\/p>\n\n\n\n
    \"\"\/<\/figure>\n\n\n\n
    Input:<\/strong> intersectVal = 0, listA = [2,6,4], listB = [1,5], skipA = 3, skipB = 2\nOutput:<\/strong> No intersection\nExplanation:<\/strong> From the head of A, it reads as [2,6,4]. From the head of B, it reads as [1,5]. Since the two lists do not intersect, intersectVal must be 0, while skipA and skipB can be arbitrary values.\nExplanation: The two lists do not intersect, so return null.\n<\/pre>\n\n\n\n
    Constraints:<\/strong><\/p>\n\n\n\n
    • The number of nodes of listA<\/code> is in the m<\/code>.<\/li>
    • The number of nodes of listB<\/code> is in the n<\/code>.<\/li>
    • 0 <= m, n <= 3 * 104<\/sup><\/code><\/li>
    • 1 <= Node.val <= 105<\/sup><\/code><\/li>
    • 0 <= skipA <= m<\/code><\/li>
    • 0 <= skipB <= n<\/code><\/li>
    • intersectVal<\/code> is 0<\/code> if listA<\/code> and listB<\/code> do not intersect.<\/li>
    • intersectVal == listA[skipA] == listB[skipB]<\/code> if listA<\/code> and listB<\/code> intersect.<\/li><\/ul>\n\n\n\n
      Follow up:<\/strong> Could you write a solution that runs in O(n)<\/code> time and use only O(1)<\/code> memory?<\/p>\n\n\n\n
      <\/p>\n\n\n\n
      Solution 1: Two Passes by swapping heads<\/strong><\/h2>\n\n\n\n
      Time complexity: O(n)
      Space complexity: O(1)<\/p>\n\n\n\n
      \n
      C++<\/h2>\n
      \n\n
      \/\/ Author: Huahua\nclass Solution {\npublic:\n  ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {\n    if (!headA || !headB) return nullptr;\n    ListNode* a = headA;\n    ListNode* b = headB;\n    while (a != b) {\n      a = a ? a->next : headB;\n      b = b ? b->next : headA;\n    }\n    return a;\n  }\n};\n<\/pre>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"
      Given the heads of two singly linked-lists headA and headB, return the node at which the two lists intersect. If the two linked lists have no intersection at all,…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[50],"tags":[222,210,83],"class_list":["post-8873","post","type-post","status-publish","format-standard","hentry","category-list","tag-easy","tag-intersection","tag-list","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/8873","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/comments?post=8873"}],"version-history":[{"count":4,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/8873\/revisions"}],"predecessor-version":[{"id":8900,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/8873\/revisions\/8900"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=8873"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=8873"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=8873"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}