[剑指offer]面试题第[52]题[Leedcode][第160题][JAVA][相交链表][双指针]

痛定思痛。 2023-02-21 11:43 27阅读 0赞

#### 【问题描述】\[简单\] ####

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70]

#### 【解答思路】 ####

###### 1. 双指针法 ######

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70 1]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70 2]  
**时间复杂度：O(N^2) 空间复杂度：O(1)**

public ListNode getIntersectionNode(ListNode headA, ListNode headB) { 
        if (headA == null || headB == null) return null;
        ListNode pA = headA, pB = headB;
        while (pA != pB) { 
            pA = pA == null ? headB : pA.next;
            pB = pB == null ? headA : pB.next;
        }
        return pA;
    }

###### 2. 双链指针同时移动，确保同时到链表尾 ######

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70 3]  
**时间复杂度：O(N+M) 空间复杂度：O(1)**

public ListNode getIntersectionNode(ListNode headA, ListNode headB) { 
            int lengthA = getLength(headA), lengthB = getLength(headB);
            ListNode a = headA, b = headB;
            if(lengthA > lengthB){ 
                for(int i = 0; i < lengthA - lengthB; i++)
                    a = a.next;
            } else { 
                for(int i = 0; i < lengthB - lengthA; i++)
                    b = b.next;
            }
            while(a != b){ 
                a = a.next;
                b = b.next;
            }
            return a;
        }
        private int getLength(ListNode head){ 
            int length = 0;
            for(ListNode temp = head; temp != null; temp = temp.next, length++);
            return length;
        }

#### 【总结】 ####

###### 1. 链表常见思路 双指针 ######

###### 2. 链表问题 画图 ######

转载链接：https://leetcode-cn.com/problems/liang-ge-lian-biao-de-di-yi-ge-gong-gong-jie-dian-lcof/solution/mian-shi-ti-52java-shuang-zhi-zhen-da-bai-100-by-u/  
转载链接：https://leetcode-cn.com/problems/intersection-of-two-linked-lists/solution/tu-jie-xiang-jiao-lian-biao-by-user7208t/

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