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rename, add, move DataStructure java code
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‎leetcode_java/src/main/java/DataStructure/BST.java‎

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package DataStructure;
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// https://github.com/yennanliu/CS_basics/blob/master/data_structure/java/BST.java
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// https://www.coursera.org/learn/algorithms-part1/lecture/7An9B/binary-search-trees
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public class BST<Key extends Comparable<Key>, Value> {
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private Node root;
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private class Node {
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private Key key;
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private Value val;
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private Node left, right;
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public Node(Key key, Value val) {
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this.key = key;
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this.val = val;
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}
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}
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// put method via recursive way
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public void put(Key key, Value val) {
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root = put(root, key, val);
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}
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private Node put(Node x, Key key, Value val) {
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if (x == null) return new Node(key, val);
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int cmp = key.compareTo(x.key);
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if (cmp < 0) x.left = put(x.left, key, val);
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else if (cmp > 0) x.right = put(x.right, key, val);
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else if (cmp == 0) x.val = val;
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return x;
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}
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public Value get(Key key) {
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Node x = root;
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while (x != null) {
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int cmp = key.compareTo(x.key);
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if (cmp < 0) x = x.left;
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else if (cmp > 0) x = x.right;
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else if (cmp == 0) return x.val;
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}
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return null;
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}
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// public void delete(Key key)
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// {}
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//
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// public Iterable<Key> iterator()
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// {}
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}

‎leetcode_java/src/main/java/DataStructure/DirectedEdge.java‎

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package DataStructure;
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// https://www.coursera.org/learn/algorithms-part2/lecture/e3UfD/shortest-paths-apis
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// https://github.com/yennanliu/CS_basics/blob/master/data_structure/java/DirectedEdge.java
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public class DirectedEdge {
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private final int v, w;
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private final double weight;
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public DirectedEdge(int v, int w, double weight) {
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this.v = v;
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this.w = w;
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this.weight = weight;
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}
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public int from() {
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return v;
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}
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public int to() {
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return w;
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}
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public int weight() {
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return (int) weight;
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}
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// Implementing "Min Heap"
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public static class MinHeap {
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// Create a complete binary tree using an array
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// Then use the binary tree to construct a Heap
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int[] minHeap;
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// the number of elements is needed when instantiating an array
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// heapSize records the size of the array
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int heapSize;
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// realSize records the number of elements in the Heap
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int realSize = 0;
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public MinHeap(int heapSize) {
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this.heapSize = heapSize;
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minHeap = new int[heapSize + 1];
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// To better track the indices of the binary tree,
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// we will not use the 0-th element in the array
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// You can fill it with any value
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minHeap[0] = 0;
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}
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// Function to add an element
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public void add(int element) {
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realSize++;
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// If the number of elements in the Heap exceeds the preset heapSize
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// print "Added too many elements" and return
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if (realSize > heapSize) {
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System.out.println("Added too many elements!");
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realSize--;
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return;
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}
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// Add the element into the array
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minHeap[realSize] = element;
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// Index of the newly added element
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int index = realSize;
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// Parent node of the newly added element
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// Note if we use an array to represent the complete binary tree
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// and store the root node at index 1
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// index of the parent node of any node is [index of the node / 2]
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// index of the left child node is [index of the node * 2]
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// index of the right child node is [index of the node * 2 + 1]
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int parent = index / 2;
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// If the newly added element is smaller than its parent node,
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// its value will be exchanged with that of the parent node
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while ( minHeap[index] < minHeap[parent] && index > 1 ) {
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int temp = minHeap[index];
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minHeap[index] = minHeap[parent];
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minHeap[parent] = temp;
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index = parent;
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parent = index / 2;
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}
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}
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// Get the top element of the Heap
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public int peek() {
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return minHeap[1];
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}
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// Delete the top element of the Heap
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public int pop() {
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// If the number of elements in the current Heap is 0,
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// print "Don't have any elements" and return a default value
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if (realSize < 1) {
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System.out.println("Don't have any element!");
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return Integer.MAX_VALUE;
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} else {
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// When there are still elements in the Heap
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// realSize >= 1
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int removeElement = minHeap[1];
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// Put the last element in the Heap to the top of Heap
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minHeap[1] = minHeap[realSize];
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realSize--;
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int index = 1;
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// When the deleted element is not a leaf node
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while (index <= realSize / 2) {
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// the left child of the deleted element
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int left = index * 2;
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// the right child of the deleted element
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int right = (index * 2) + 1;
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// If the deleted element is larger than the left or right child
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// its value needs to be exchanged with the smaller value
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// of the left and right child
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if (minHeap[index] > minHeap[left] || minHeap[index] > minHeap[right]) {
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if (minHeap[left] < minHeap[right]) {
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int temp = minHeap[left];
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minHeap[left] = minHeap[index];
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minHeap[index] = temp;
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index = left;
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} else {
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// maxHeap[left] >= maxHeap[right]
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int temp = minHeap[right];
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minHeap[right] = minHeap[index];
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minHeap[index] = temp;
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index = right;
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}
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} else {
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break;
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}
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}
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return removeElement;
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}
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}
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// return the number of elements in the Heap
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public int size() {
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return realSize;
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}
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public String toString() {
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if (realSize == 0) {
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return "No element!";
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} else {
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StringBuilder sb = new StringBuilder();
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sb.append('[');
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for (int i = 1; i <= realSize; i++) {
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sb.append(minHeap[i]);
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sb.append(',');
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}
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sb.deleteCharAt(sb.length() - 1);
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sb.append(']');
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return sb.toString();
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}
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}
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public static void main(String[] args) {
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// Test case
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MinHeap minHeap = new MinHeap(3);
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minHeap.add(3);
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minHeap.add(1);
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minHeap.add(2);
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// [1,3,2]
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System.out.println(minHeap.toString());
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// 1
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System.out.println(minHeap.peek());
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// 1
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System.out.println(minHeap.pop());
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// [2, 3]
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System.out.println(minHeap.toString());
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minHeap.add(4);
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// Add too many elements
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minHeap.add(5);
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// [2,3,4]
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System.out.println(minHeap.toString());
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}
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}
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}

‎leetcode_java/src/main/java/DataStructure/ListNode.java‎

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package DataStructure;
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// https://github.com/yennanliu/CS_basics/blob/master/data_structure/java/LinkedinList.java
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// https://github.com/youngyangyang04/leetcode-master/blob/master/problems/%E9%93%BE%E8%A1%A8%E7%90%86%E8%AE%BA%E5%9F%BA%E7%A1%80.md
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public class ListNode {
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// 结点的值
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int val;
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// 下一个结点
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ListNode next;
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// 节点的构造函数(无参)
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public ListNode() {
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}
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// 节点的构造函数(有一个参数)
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public ListNode(int val) {
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this.val = val;
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}
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// 节点的构造函数(有两个参数)
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public ListNode(int val, ListNode next) {
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this.val = val;
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this.next = next;
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}
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}

‎leetcode_java/src/main/java/AlgorithmJava/MaxHeap.java‎ renamed to ‎leetcode_java/src/main/java/DataStructure/MaxHeap.java‎

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package AlgorithmJava;
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package DataStructure;
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// https://leetcode.com/explore/learn/card/heap/643/heap/4017/
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‎leetcode_java/src/main/java/AlgorithmJava/MinHeap.java‎ renamed to ‎leetcode_java/src/main/java/DataStructure/MinHeap.java‎

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package AlgorithmJava;
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package DataStructure;
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// https://leetcode.com/explore/learn/card/heap/643/heap/4017/
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