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Intuition\n Describe your first thoughts on how to solve this problem. \nThe problem requires merging two linked lists list1 and list2 by removing a segment of 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\nThe problem requires merging two linked lists list1 and list2 by removing a segment of nodes from list1 and replacing them with list2. To solve this, we can traverse list1 to identify the nodes to be removed (from position a to position b), connect the node just before a to the head of list2, and connect the last node of list2 to the node after b.\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\nIdentifying Nodes to Remove: We traverse list1 to find the node just before position a and the node at position b. This step ensures that we can properly connect list2 without losing track of the nodes in list1.\n\nConnecting list2: Once we have identified the nodes to remove in list1, we connect the node just before a to the head of list2. This effectively places list2 in the segment that needs to be removed from list1.\n\nConnecting the Tail of list2: After connecting the head of list2, we traverse to the end of list2 to find its last node. We then connect this last node to the node after b in list1. This step effectively merges list2 into list1.\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\nTraversing list1 to find the nodes at positions a and b: This takes linear time, proportional to the size of list1, so it\'s O(n), where n is the size of list1.\nTraversing list2 to find its last node: Similarly, this takes linear time, so it\'s O(m), where m is the size of list2.Overall, the time complexity is O(n+m).\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\nWe\'re using constant space for variables, and we\'re not creating any additional data structures proportional to the size of the input lists. Hence, the space complexity is O(1).\n\n# DryRun\nLet\'s dry run the algorithm with an example:\n\nlist1 = [10, 1, 13, 6, 9, 5]\na = 3, b = 4\nlist2 = [1000000, 1000001, 1000002]\nWe start with list1 and traverse to the node just before position a (which is the 2nd node with value 1) and the node at position b (which is the 3rd node with value 6).\n\nWe connect the node just before a to the head of list2, making list1 look like [10, 1, 1000000, 1000001, 1000002, 9, 5].\n\nWe traverse list2 to find its last node, which is the 3rd node with value 1000002. We connect this last node to the node after b in list1, effectively merging list2 into list1.\n\nThe final merged list is [10, 1, 1000000, 1000001, 1000002, 9, 5].\n\n# Code\n```\nclass Solution {\n    public ListNode mergeInBetween(ListNode list1, int a, int b, ListNode list2) {\n        if (list2 == null) {\n            return list1; \n        }\n        \n        ListNode temp = list1;\n        \n       \n        for (int i = 0; i < a - 1; i++) {\n            temp = temp.next;\n        }\n        \n        ListNode beforeA = temp;\n       \n        for (int i = 0; i < b - a + 1; i++) {\n            temp = temp.next;\n        }\n    \n        ListNode afterB = temp.next;\n        \n        beforeA.next = list2;\n        \n        while (list2.next != null) {\n            list2 = list2.next;\n        }\n        \n        list2.next = afterB;\n        \n        return list1;\n    }\n}\n\n\n```
['Java']