深圳同城快跑笔试题目 3 实现四则运算
package com.cici.深圳同城快跑; import java.util.Stack; class Node { public char cData; // data item (key) public Node leftChild; // this node's left child public Node rightChild; // this node's right child public void displayNode() // display ourself { System.out.print('{'); System.out.print(cData); System.out.print("} "); } } // end class Node class Tree { public Node root; // first node of tree public int size; //------------------------------------------------------------- public Tree() // constructor { root = null; } // no nodes in tree yet //------------------------------------------------------------- public Node find(char key) // find node with given key { // (assumes non-empty tree) Node current = root; // start at root while(current.cData != key) // while no match, { if(key < current.cData) // go left? current = current.leftChild; else // or go right? current = current.rightChild; if(current == null) // if no child, return null; // didn't find it } return current; // found it } // end find() //------------------------------------------------------------- public void insert(char c) { Node newNode = new Node(); // make new node newNode.cData = c; // insert data if(root==null) // no node in root root = newNode; else // root occupied { //make a new node which is stands for the new node Node current = root; // start at root Node parent; while(true) // (exits internally) { //parent node is the root node parent = current; //go left ? if(check(c)){ current = current.leftChild; if(current == null) // if end of the line, { // insert on left parent.leftChild = newNode; return; } } // end if go left else // or go right? { current = current.leftChild; if(current == null) // if end of the line { // insert on right parent.rightChild = newNode; return; } } // end else go right } // end while } // end else not root } // end insert() //------------------------------------------------------------- public boolean delete(char key) // delete node with given key { // (assumes non-empty list) Node current = root; Node parent = root; boolean isLeftChild = true; while(current.cData != key) // search for node { parent = current; if(key < current.cData) // go left? { isLeftChild = true; current = current.leftChild; } else // or go right? { isLeftChild = false; current = current.rightChild; } if(current == null) // end of the line, return false; // didn't find it } // end while // found node to delete // if no children, simply delete it if(current.leftChild==null && current.rightChild==null) { if(current == root) // if root, root = null; // tree is empty else if(isLeftChild) parent.leftChild = null; // disconnect else // from parent parent.rightChild = null; } // if no right child, replace with left subtree else if(current.rightChild==null) if(current == root) root = current.leftChild; else if(isLeftChild) parent.leftChild = current.leftChild; else parent.rightChild = current.leftChild; // if no left child, replace with right subtree else if(current.leftChild==null) if(current == root) root = current.rightChild; else if(isLeftChild) parent.leftChild = current.rightChild; else parent.rightChild = current.rightChild; else // two children, so replace with inorder successor { // get successor of node to delete (current) Node successor = getSuccessor(current); // connect parent of current to successor instead if(current == root) root = successor; else if(isLeftChild) parent.leftChild = successor; else parent.rightChild = successor; // connect successor to current's left child successor.leftChild = current.leftChild; } // end else two children // (successor cannot have a left child) return true; // success } // end delete() //------------------------------------------------------------- // returns node with next-highest value after delNode // goes to right child, then right child's left descendents private Node getSuccessor(Node delNode) { Node successorParent = delNode; Node successor = delNode; Node current = delNode.rightChild; // go to right child while(current != null) // until no more { // left children, successorParent = successor; successor = current; current = current.leftChild; // go to left child } // if successor not if(successor != delNode.rightChild) // right child, { // make connections successorParent.leftChild = successor.rightChild; successor.rightChild = delNode.rightChild; } return successor; } //------------------------------------------------------------- public void traverse(int traverseType) { switch(traverseType) { case 1: System.out.print("\nPreorder traversal: "); preOrder(root); break; case 2: System.out.print("\nInorder traversal: "); inOrder(root); break; case 3: System.out.print("\nPostorder traversal: "); postOrder(root); break; } System.out.println(); } //------------------------------------------------------------- public void preOrder(Node localRoot) { if(localRoot != null) { preOrder(localRoot.leftChild); System.out.print(localRoot.cData + " "); preOrder(localRoot.rightChild); } } //------------------------------------------------------------- public Node inOrder(Node localRoot) { if(localRoot != null) { inOrder(localRoot.leftChild); System.out.print(localRoot.cData + " "); inOrder(localRoot.rightChild); } return localRoot; } //------------------------------------------------------------- public void postOrder(Node localRoot) { if(localRoot != null) { postOrder(localRoot.leftChild); postOrder(localRoot.rightChild); System.out.print(localRoot.cData + " "); } } //check the whether a node is a signal public static boolean check(Character ch){ if(ch.equals(new Character('+')) || ch.equals(new Character('-')) || ch.equals(new Character('*')) || ch.equals(new Character('\\') ) || ch.equals(new Character('^')) ) { return true; } return false; } public long calculate( ){ long result = 0; result+=this.root.cData-48; Node localRoot= root.leftChild; while(localRoot!=null){ if(localRoot.cData=='+'){ if(localRoot.rightChild!=null){ result+=localRoot.rightChild.cData-48; } } if(localRoot.cData=='-'){ if(localRoot.rightChild!=null){ result-=localRoot.rightChild.cData-48; } } if(localRoot.cData=='/'){ if(localRoot.rightChild!=null){ result/=localRoot.rightChild.cData-48; } } if(localRoot.cData=='*'){ if(localRoot.rightChild!=null){ result*=localRoot.rightChild.cData-48; } } /*int m = 4; int n = 2; int result = 1; for(int i=0;i<n;i++){ result*=m; } System.out.println(result);*/ if(localRoot.cData=='^'){ long temp = 1; for(int i=0;i<localRoot.rightChild.cData-48;i++){ temp*=result; } result= temp; } localRoot= localRoot.leftChild; } return result; } //------------------------------------------------------------- public void displayTree() { Stack globalStack = new Stack(); globalStack.push(root); int nBlanks = 32; boolean isRowEmpty = false; System.out.println( "......................................................"); while(isRowEmpty==false) { Stack localStack = new Stack(); isRowEmpty = true; for(int j=0; j<nBlanks; j++) System.out.print(' '); while(globalStack.isEmpty()==false) { Node temp = (Node)globalStack.pop(); if(temp != null) { System.out.print(temp.cData); localStack.push(temp.leftChild); localStack.push(temp.rightChild); if(temp.leftChild != null || temp.rightChild != null) isRowEmpty = false; } else { System.out.print("--"); localStack.push(null); localStack.push(null); } for(int j=0; j<nBlanks*2-2; j++) System.out.print(' '); } // end while globalStack not empty System.out.println(); nBlanks /= 2; while(localStack.isEmpty()==false) globalStack.push( localStack.pop() ); } // end while isRowEmpty is false System.out.println( "......................................................"); } // end displayTree() //------------------------------------------------------------- } // end class Tree public class TreeApp{ public static void main(String[] args) { Tree tree = new Tree(); tree.insert('2'); tree.insert('^'); tree.insert('3'); tree.insert('+'); tree.insert('1'); tree.insert('*'); tree.insert('2'); tree.displayTree(); long result = tree.calculate(); System.out.println("----"+result+"----"); } }
以上代码没有考虑优先级别顺序 以下代码考虑四则运算符号有限级别 先* / ^ 再 + -
但是没有输出正确答案.因为calculate()方法还是有误.以此本人得到的结论利用节点树形结构太复杂了.尽量避免.本人有空闲时间会参考jdk的tree.
不过依然太难了.调试很多次都没有输出正确结果.今天打算放弃了.有会修改程序的高手希望您看到了改一下.我实在不想改了.
package com.cici.深圳同城快跑; import java.util.Stack; class Node { public char cData; // data item (key) public Node leftChild; // this node's left child public Node rightChild; // this node's right child public Node(char cData){ this.cData = cData; } public void displayNode() // display ourself { System.out.print('{'); System.out.print(cData); System.out.print("} "); } } // end class Node class Tree { public Node root; // first node of tree public int size; //------------------------------------------------------------- public Tree() // constructor { root = null; } // no nodes in tree yet //------------------------------------------------------------- public Node find(char key) // find node with given key { // (assumes non-empty tree) Node current = root; // start at root while(current.cData != key) // while no match, { if(key < current.cData) // go left? current = current.leftChild; else // or go right? current = current.rightChild; if(current == null) // if no child, return null; // didn't find it } return current; // found it } // end find() //------------------------------------------------------------- public void insert(char c) { Node newNode = new Node(c); // make new node if(root==null&&!check(c)){ root = new Node(' '); root.rightChild=newNode; size++; return; } // no node in root else if(root!=null&!check(root.cData)){ Node temp = root.rightChild; root=new Node(c); root.rightChild=temp; size++; return; } else // root occupied { //make a new node which is stands for the new node Node current = root; // start at root Node parent; while(true) // (exits internally) { //parent node is the root node parent = current; //go left ? if(check(c)){ current = current.leftChild; if(current.cData == ' ') // if end of the line, { // insert on left newNode=new Node(c); newNode.rightChild=current.rightChild; parent.leftChild = newNode; size++; return; } else continue; } // end if go left else // or go right? { current = current.leftChild; if(current == null) // if end of the line { // insert on right newNode = new Node(' '); // make new node newNode.rightChild=new Node(c); parent.leftChild = newNode; size++; return; } } // end else go right } // end while } // end else not root } // end insert() //------------------------------------------------------------- public boolean delete(char key) // delete node with given key { // (assumes non-empty list) Node current = root; Node parent = root; boolean isLeftChild = true; while(current.cData != key) // search for node { parent = current; if(key < current.cData) // go left? { isLeftChild = true; current = current.leftChild; } else // or go right? { isLeftChild = false; current = current.rightChild; } if(current == null) // end of the line, return false; // didn't find it } // end while // found node to delete // if no children, simply delete it if(current.leftChild==null && current.rightChild==null) { if(current == root) // if root, root = null; // tree is empty else if(isLeftChild) parent.leftChild = null; // disconnect else // from parent parent.rightChild = null; } // if no right child, replace with left subtree else if(current.rightChild==null) if(current == root) root = current.leftChild; else if(isLeftChild) parent.leftChild = current.leftChild; else parent.rightChild = current.leftChild; // if no left child, replace with right subtree else if(current.leftChild==null) if(current == root) root = current.rightChild; else if(isLeftChild) parent.leftChild = current.rightChild; else parent.rightChild = current.rightChild; else // two children, so replace with inorder successor { // get successor of node to delete (current) Node successor = getSuccessor(current); // connect parent of current to successor instead if(current == root) root = successor; else if(isLeftChild) parent.leftChild = successor; else parent.rightChild = successor; // connect successor to current's left child successor.leftChild = current.leftChild; } // end else two children // (successor cannot have a left child) return true; // success } // end delete() //------------------------------------------------------------- // returns node with next-highest value after delNode // goes to right child, then right child's left descendents private Node getSuccessor(Node delNode) { Node successorParent = delNode; Node successor = delNode; Node current = delNode.rightChild; // go to right child while(current != null) // until no more { // left children, successorParent = successor; successor = current; current = current.leftChild; // go to left child } // if successor not if(successor != delNode.rightChild) // right child, { // make connections successorParent.leftChild = successor.rightChild; successor.rightChild = delNode.rightChild; } return successor; } //------------------------------------------------------------- public void traverse(int traverseType) { switch(traverseType) { case 1: System.out.print("\nPreorder traversal: "); preOrder(root); break; case 2: System.out.print("\nInorder traversal: "); inOrder(root); break; case 3: System.out.print("\nPostorder traversal: "); postOrder(root); break; } System.out.println(); } //------------------------------------------------------------- public void preOrder(Node localRoot) { if(localRoot != null) { preOrder(localRoot.leftChild); System.out.print(localRoot.cData + " "); preOrder(localRoot.rightChild); } } //------------------------------------------------------------- public Node inOrder(Node localRoot) { if(localRoot != null) { inOrder(localRoot.leftChild); System.out.print(localRoot.cData + " "); inOrder(localRoot.rightChild); } return localRoot; } //------------------------------------------------------------- public void postOrder(Node localRoot) { if(localRoot != null) { postOrder(localRoot.leftChild); postOrder(localRoot.rightChild); System.out.print(localRoot.cData + " "); } } //check the whether a node is a signal public static boolean check(Character ch){ if(ch.equals(new Character('+')) || ch.equals(new Character('-')) || ch.equals(new Character('*')) || ch.equals(new Character('/') ) || ch.equals(new Character('^')) ) { return true; } return false; } public long calculate(){ Node current = this.root; Node parent = this.root; long result = 0; //handle * / ^ while(current.cData!=' '){ int item1 = current.rightChild.cData-48; int item2 = current.leftChild.rightChild.cData-48; long temp = 1; if(current!=null && current.cData=='*'){ result =item1*item2; Node next = current.leftChild; next.rightChild=new Node(((char) (result+48))); // parent.cData=next.cData; parent.leftChild = next; current = next; continue; }if(current!=null && current.cData=='/'){ result =item1/item2; Node next = current.leftChild; next.rightChild=new Node(((char) (result+48))); // parent.cData=next.cData; parent.leftChild = next; current = next; continue; }if(current!=null && current.cData=='^'){ for(int i=0;i<item2;i++){ temp*=result; } result = temp; Node next = current.leftChild; next.rightChild=new Node(((char) (result+48))); // parent.cData=next.cData; parent.leftChild = next; current = next; continue; } parent=current; current = current.leftChild; } //handle + - //parent = root; root.leftChild =parent; parent = root; current = root; while(current.leftChild!=null ){ result = 0; int item1 = parent.rightChild.cData-48; int item2 = parent.leftChild.rightChild.cData-48; //long temp = 1; if(parent.cData=='+'){ result +=item1+item2; }if(parent.cData=='-'){ result +=item1-item2; } current = current.leftChild; parent=current; } return result; } //------------------------------------------------------------- public void displayTree() { Stack globalStack = new Stack(); globalStack.push(root); int nBlanks = 32; boolean isRowEmpty = false; System.out.println( "......................................................"); while(isRowEmpty==false) { Stack localStack = new Stack(); isRowEmpty = true; for(int j=0; j<nBlanks; j++) System.out.print(' '); while(globalStack.isEmpty()==false) { Node temp = (Node)globalStack.pop(); if(temp != null) { System.out.print(temp.cData); localStack.push(temp.leftChild); localStack.push(temp.rightChild); if(temp.leftChild != null || temp.rightChild != null) isRowEmpty = false; } else { System.out.print("--"); localStack.push(null); localStack.push(null); } for(int j=0; j<nBlanks*2-2; j++) System.out.print(' '); } // end while globalStack not empty System.out.println(); nBlanks /= 2; while(localStack.isEmpty()==false) globalStack.push( localStack.pop() ); } // end while isRowEmpty is false System.out.println( "......................................................"); } // end displayTree() //------------------------------------------------------------- } // end class Tree public class TreeApp{ public static void main(String[] args) { Tree tree = new Tree(); tree.insert('1'); tree.insert('+'); tree.insert('6'); tree.insert('/');//2+6/2*3^2+3 tree.insert('2'); tree.insert('*'); tree.insert('3'); tree.insert('^'); tree.insert('2'); tree.insert('+'); tree.insert('7'); tree.displayTree(); long result = tree.calculate(); System.out.println("----"+result+"----"); } }
