public static void main(String[] args) {
ListNode a = new ListNode('1');
ListNode b = new ListNode('2');
ListNode c = new ListNode('3');
ListNode d = new ListNode('1');
ListNode e = new ListNode(' ');
ListNode f = new ListNode('3');
a.next = b;
b.next = c;
c.next = d;
d.next = e;
e.next = f;
System.out.println(a);
removeDupes(a);
System.out.println("After removing duplicate ListNodes: ");
System.out.println(a);
}
public ListNode partition(ListNode head, int x) {
ListNode headOfHead = new ListNode(-1);
headOfHead.next = head;
ListNode p = headOfHead;
while (p.next != null) {
p = p.next;
// CUT begin
debug(p.val);
// CUT end
}
ListNode tail = new ListNode(-1);
p.next = tail;
p = headOfHead;
ListNode q = tail;
while (p.next != tail) {
if (p.next.val < x) {
p = p.next;
} else {
q.next = p.next;
q = q.next;
p.next = p.next.next;
q.next = null;
}
}
p.next = tail.next;
return headOfHead.next;
}
public ListNode deleteDuplicates(ListNode a) {
ListNode temp = a;
LinkedHashMap<Integer, Integer> map = new LinkedHashMap<Integer, Integer>();
int i = 0;
while (temp != null) {
if (map.get(temp.val) == null) {
map.put(temp.val, 1);
} else {
map.put(temp.val, map.get(temp.val) + 1);
}
temp = temp.next;
}
System.out.println(map);
Iterator<Integer> it = map.keySet().iterator();
ListNode root = null;
ListNode root1 = null;
while (it.hasNext()) {
int x = it.next();
if (map.get(x) == 1) {
if (root == null) {
root = new ListNode(x);
root1 = root;
} else {
ListNode node = new ListNode(x);
root1.next = node;
root1 = node;
}
}
}
return root;
}
/*
Solution 2
Did not use additional space, each time encounter the first unique value node,
traversal the rest of the list to delete the same value's nodes.
Assumption:
None.
Time complexity: O(n^2)
Space Complexity: O(1)
*/
private static ListNode RemoveDups2(ListNode head) {
if (head == null) return head;
ListNode pre = head;
while (pre != null) {
ListNode pre2 = pre;
ListNode cur = pre.next;
int target = pre.val;
while (cur != null) { // delete the dups in the rest of the list
if (cur.val == target) {
pre2.next = cur.next;
cur = cur.next;
} else {
pre2 = cur;
cur = cur.next;
}
}
// move to next different value's node
pre = pre.next;
}
return head;
}
/* Helpers */
private static InputArgs input() throws IOException {
System.out.println("2.2 Return Kth to Last");
// read K
System.out.print("Please input K: ");
Scanner sc = new Scanner(System.in);
int k = sc.nextInt();
// read number of nodes
System.out.println();
System.out.print("Please input the number of nodes in the linked list: ");
int n = sc.nextInt();
// read linked list
System.out.println();
System.out.print("Please input value of nodes (seperate by space, e.g., 1 2 3): ");
ListNode dummy = new ListNode(0);
ListNode pre = dummy;
for (int i = 0; i < n; i++) {
ListNode cur = new ListNode(sc.nextInt());
pre.next = cur;
pre = cur;
}
return new InputArgs(k, dummy.next);
}
public void solve(InputReader in, OutputWriter out) {
int n = in.nextInt();
int x = in.nextInt();
ListNode head = new ListNode(-1);
ListNode p = head;
for (int i = 0; i < n; i++) {
p.next = new ListNode(in.nextInt());
p = p.next;
// out.println(p.val);
}
ListNode res = new A1().partition(head.next, x);
p = res;
while (p != null) {
out.println(p.val);
p = p.next;
}
}
public static void removeDupes(ListNode ListNode) {
Set<Integer> set = new HashSet<Integer>();
// add the first ListNode
set.add(ListNode.val);
ListNode prev = ListNode;
ListNode curr = ListNode.next;
while (curr != null) {
// already exists, delete this duplicate one
if (set.contains(curr.val)) {
prev.next = curr.next;
} else {
set.add(curr.val);
prev = curr;
}
curr = curr.next;
}
}
/*
Solution 1
Using hashtable to record nodes, delete the node if the same value already exists.
Assumption:
None.
Time complexity: O(n)
Space Complexity: O(n)
*/
private static ListNode RemoveDups1(ListNode head) {
if (head == null) return head;
Set<Integer> set = new HashSet<Integer>();
ListNode pre = head;
ListNode cur = head.next;
set.add(head.val);
while (cur != null) {
if (set.contains(cur.val)) { // delete dup
pre.next = cur.next;
cur = cur.next;
} else {
set.add(cur.val);
pre = cur;
cur = cur.next;
}
}
return head;
}
// input
private static ListNode input() {
ListNode dummyhead = new ListNode(0);
ListNode pre = dummyhead;
System.out.println("/**** 2.1 Remove Dups ****/");
System.out.println("Please input a linked list (using space to seperate nodes): ");
try {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String s = br.readLine();
String[] nodes = s.split(" ");
for (int i = 0; i < nodes.length; i++) {
ListNode cur = new ListNode(Integer.parseInt(nodes[i]));
pre.next = cur;
pre = cur;
}
} catch (IOException e) {
System.out.println("input error, " + e.getMessage());
}
return dummyhead.next;
}