程序员面试题：常见数据结构的实现（JAVA版）

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1、链表

class Node {Node next = null;int data;/* * 构造一个节点 */public Node(int d){data = d;}/* * 添加元素d到链表 */void appendToTail(int d){Node end = new Node(d);Node n = this;while(n.next != null){n = n.next;}n.next = end;}/* * 从头节点为head的链表删除元素d */Node deleteNode(Node head, int d){Node n = head;if(head == null)return null;if(head.data == d)return head.next;while(n.next != null){if(n.next.data == d){n.next = n.next.next;}}return head;}}

2、堆栈

/* * 用链表实现堆栈 */class Stack {//top指向栈顶元素Node top;int pop(){/* * 如果堆栈非空，将栈顶元素弹出 */if(top == null){return 0;}int item = top.data;top = top.next;return item;}void push(int item){/* * 将元素压人堆栈 */Node t = new Node(item);t.next = top;top = t;}Object peek(){/* * 返回栈顶元素 */return top.data;}}

3、队列

/* * 用链表实现队列 */class Queue {//first指向队列头，end指向队列尾Node first, last;//将元素添加进队列void enqueue(int item){if(first == null){last = first = new Node(item);}else{last.next = new Node(item);last = last.next;}}//出队列操作int dequeue(){if(first == null){return 0;}int item = first.data;first = first.next;return item;}}

4、图遍历

class Solution {/*   class Node {     Node next = null;     int data;     boolean visited;     ArrayList<Node> adjacent;   }*///访问节点void visit(Node root){//methods}//深度优先搜索,递归实现void dfs(Node root){if(root == null)return;visit(root);root.visited = true;for(Node n : root.adjacent){if(n.visited == false){dfs(n);}}}//广度优先搜索，队列实现void bfs(Node root){java.util.Queue<Node> queue = new java.util.LinkedList();root.visited = true;visit(root);queue.add(root);while(!queue.isEmpty()){Node r = queue.remove();for(Node n : r.adjacent){if(n.visited == false){n.visited = true;visit(n);queue.add(n);}}}}}

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