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/**

* Design a HashSet without using any built-in hash table libraries.

*

* To be specific, your design should include these functions:

* add(value): Insert a value into the HashSet.

* contains(value) : Return whether the value exists in the HashSet or not.

* remove(value): Remove a value in the HashSet. If the value does not exist

* in the HashSet, do nothing.

*

* Example:

* MyHashSet hashSet = new MyHashSet();

* hashSet.add(1);

* hashSet.add(2);

* hashSet.contains(1); // returns true

* hashSet.contains(3); // returns false (not found)

* hashSet.add(2);

* hashSet.contains(2); // returns true

* hashSet.remove(2);

* hashSet.contains(2); // returns false (already removed)

*

* Note:

* All values will be in the range of [0, 1000000].

* The number of operations will be in the range of [1, 10000].

* Please do not use the built-in HashSet library.

*/

public class DesignHashSet705 {

class MyHashSet {

private static final int K = 10000;

private List<Integer>[] cache = new List[K];

/** Initialize your data structure here. */

public MyHashSet() {

}

public void add(int key) {

int k = key % K;

if (cache[k] == null) {

cache[k] = new ArrayList<>();

}

List<Integer> list = cache[k];

for (int el: list) {

if (el == key) return;

}

list.add(key);

}

public void remove(int key) {

int k = key % K;

if (cache[k] == null) return;

List<Integer> list = cache[k];

for (int i=0; i<list.size(); i++) {

if (list.get(i) == key) {

list.remove(i);

return;

}

}

}

/** Returns true if this set contains the specified element */

public boolean contains(int key) {

int k = key % K;

if (cache[k] == null) return false;

List<Integer> list = cache[k];

for (int el: list) {

if (el == key) return true;

}

return false;

}

}

class MyHashSet2 {

private static final int K = 10000;

private TreeNode[] cache = new TreeNode[K];

/** Initialize your data structure here. */

public MyHashSet2() {

}

public void add(int key) {

int k = key % K;

cache[k] = addNode(cache[k], key);

}

TreeNode addNode(TreeNode root, int key) {

if (root == null) return new TreeNode(key);

if (root.key > key) {

root.left = addNode(root.left, key);

} else if (root.key < key) {

root.right = addNode(root.right, key);

}

return root;

}

public void remove(int key) {

int k = key % K;

cache[k] = removeNode(cache[k], key);

}

TreeNode removeNode(TreeNode root, int key) {

if (root == null) return null;

if (root.key > key) {

root.left = removeNode(root.left, key);

} else if (root.key < key) {

root.right = removeNode(root.right, key);

} else {

if (root.left == null) {

return root.right;

} else if (root.right == null) {

return root.left;

} else {

root.key = findMin(root.right);

root.right = removeNode(root.right, root.key);

}

}

return root;

}

int findMin(TreeNode root) {

while (root.left != null) {

root = root.left;

}

return root.key;

}

/** Returns true if this set contains the specified element */

public boolean contains(int key) {

return containNode(cache[key % K], key);

}

boolean containNode(TreeNode root, int key) {

if (root == null) return false;

if (root.key == key) return true;

return containNode(root.left, key) || containNode(root.right, key);

}

class TreeNode {

TreeNode left;

TreeNode right;

int key;

TreeNode(int key) {

this.key = key;

}

}

}

/**

* Your MyHashSet object will be instantiated and called as such:

* MyHashSet obj = new MyHashSet();

* obj.add(key);

* obj.remove(key);

* boolean param_3 = obj.contains(key);

*/

}