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| 1 | + |
| 2 | + |
| 3 | + |
| 4 | +/**PROBLEM |
| 5 | + * You are given the head of a linked list containing unique integer values and an integer array nums |
| 6 | + *that is a subset of the linked list values. |
| 7 | +
|
| 8 | +*Return the number of connected components in nums where two values are connected if |
| 9 | + *they appear consecutively in the linked list. |
| 10 | +*/ |
| 11 | + |
| 12 | +// SAMPLE I/O |
| 13 | +// Input: head = [0,1,2,3], nums = [0,1,3] |
| 14 | +// Output: 2 |
| 15 | +// Explanation: 0 and 1 are connected, so [0, 1] and [3] are the two connected components. |
| 16 | + |
| 17 | +// Approach |
| 18 | +/** |
| 19 | + * Creating a HashMap to store all the values of nums[] |
| 20 | + * Iterating list and if current node(head) we check if the hashmap contains the value] |
| 21 | + * if yes the we increment the ans by one and setting the flag to false |
| 22 | + * |
| 23 | + * |
| 24 | + * |
| 25 | + * Time Complexity: O(N) |
| 26 | + * Space Complexity : O(N) |
| 27 | + */ |
| 28 | + |
| 29 | + |
| 30 | +/** |
| 31 | + * Definition for singly-linked list. |
| 32 | + * public class ListNode { |
| 33 | + * int val; |
| 34 | + * ListNode next; |
| 35 | + * ListNode() {} |
| 36 | + * ListNode(int val) { this.val = val; } |
| 37 | + * ListNode(int val, ListNode next) { this.val = val; this.next = next; } |
| 38 | + * } |
| 39 | + */ |
| 40 | +class Solution { |
| 41 | + public int numComponents(ListNode head, int[] nums) { |
| 42 | + // Create a HashMap to store the values from nums as keys and their indices as values |
| 43 | + HashMap<Integer, Integer> hm = new HashMap<>(); |
| 44 | + for (int i = 0; i < nums.length; i++) { |
| 45 | + hm.put(nums[i], i); |
| 46 | + } |
| 47 | + |
| 48 | + boolean flag = true; // Flag to track if a connected component is found |
| 49 | + int ans = 0; // Variable to store the number of connected components |
| 50 | + |
| 51 | + // Traverse the linked list |
| 52 | + while (head != null) { |
| 53 | + // Check if the current node's value is present in the HashMap |
| 54 | + while (head != null && hm.containsKey(head.val)) { |
| 55 | + head = head.next; // Move to the next node |
| 56 | + |
| 57 | + // If this is the start of a new connected component, increment the answer |
| 58 | + if (flag) { |
| 59 | + ans += 1; |
| 60 | + flag = false; |
| 61 | + } |
| 62 | + } |
| 63 | + flag = true; // Reset the flag |
| 64 | + |
| 65 | + if (head != null) { |
| 66 | + head = head.next; // Move to the next node |
| 67 | + } |
| 68 | + } |
| 69 | + |
| 70 | + return ans; |
| 71 | + } |
| 72 | +} |
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