LeetCode：移除重复节点-java实现

package com.chenbin.demo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Set;

public class Day0626 {
public static ListNode removeDuplicateNodes(ListNode head) {

if (head == null || head.next == null) {
return head;
        }
        Set<Integer> set = new HashSet<>();
        ListNode p = head;
set.add(p.val);
while (p.next != null ) {
if (set.contains(p.next.val)) {
                p.next = p.next.next;
            }else {
set.add(p.next.val);
                p = p.next;
            }
        }
return head;
    }

public static int[] stringToIntegerArray(String input) {
        input = input.trim();
        input = input.substring(1, input.length() - 1);
if (input.length() == 0) {
return new int[0];
        }

        String[] parts = input.split(",");
int[] output = new int[parts.length];
for (int index = 0; index < parts.length; index++) {
            String part = parts[index].trim();
            output[index] = Integer.parseInt(part);
        }
return output;
    }

public static ListNode stringToListNode(String input) {
// Generate array from the input
int[] nodeValues = stringToIntegerArray(input);

// Now convert that list into linked list
        ListNode dummyRoot = new ListNode(0);
        ListNode ptr = dummyRoot;
for (int item : nodeValues) {
            ptr.next = new ListNode(item);
            ptr = ptr.next;
        }
return dummyRoot.next;
    }

public static String listNodeToString(ListNode node) {
if (node == null) {
return "[]";
        }

        String result = "";
while (node != null) {
            result += Integer.toString(node.val) + ", ";
            node = node.next;
        }
return "[" + result.substring(0, result.length() - 2) + "]";
    }

public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String line;
while ((line = in.readLine()) != null) {
            ListNode head = stringToListNode(line);

            ListNode ret = removeDuplicateNodes(head);

            String out = listNodeToString(ret);

            System.out.print(out);
        }
    }

}

class ListNode {
int val;
    ListNode next;

    ListNode(int x) {
        val = x;
    }
}