Examples with ListNode com.fishercoder.common.classes.ListNode used on opensource projects

Example 26 with ListNode

use of com.fishercoder.common.classes.ListNode in project Leetcode by fishercoder1534.

the class _203 method removeElements.

/**
 * This is a very good question to test your understanding of pointers/memory/addresses, although it's marked as EASY.
 * All the three nodes: dummy, curr and prev are indispensable.
 * <p>
 * 1. Eventually, we should return dummy.next as the final result.
 * 2. we assign head to curr, dummy to prev
 * 3. and then we use prev and curr to traverse through the list and do the work
 * 4. each time, we only move one node forward, so we don't need another while loop inside the while loop
 * 5. KEY: if(curr.val == val), then curr is the node we want to remove, so, we'll assign curr.next to prev.next, thus, prev won't have that node
 * else, we'll keep moving prev forward, so, just do prev = prev.next
 * but, for both cases, we'll also move curr forward, so we put curr = curr.next in the outside.
 */
public ListNode removeElements(ListNode head, int val) {
    ListNode dummy = new ListNode(-1);
    dummy.next = head;
    ListNode curr = head;
    ListNode prev = dummy;
    while (curr != null) {
        if (curr.val == val) {
            prev.next = curr.next;
        } else {
            prev = prev.next;
        }
        curr = curr.next;
    }
    return dummy.next;
}