2022-10-13

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[gongpeione]

19 Remove Nth Node From End of List

/*
 * @lc app=leetcode id=19 lang=typescript
 *
 * [19] Remove Nth Node From End of List
 */

// @lc code=start
/**
 * Definition for singly-linked list.
 * class ListNode {
 *     val: number
 *     next: ListNode | null
 *     constructor(val?: number, next?: ListNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.next = (next===undefined ? null : next)
 *     }
 * }
 */

function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null {
    const dummy = new ListNode(0, head);

    // the distance between left and right is always n
    let left = dummy;
    let right = head;
    for (let i = 0; i < n; i++) {
        right = right.next;
    }

    // right will reach the end of this list
    // and left would be the prev node of target node that we need to delete
    while (right) {
        left = left.next;
        right = right.next;
    }

    // delete the node
    left.next = left.next.next;

    return dummy.next;
};
// @lc code=end

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Nickname: Geeku
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