类广义表到树

树是一种重要的数据结构，下面是如：(a b(c d) aa (bb cc dd) ee(ff ( gg (h i j)))) 这样的类广义表读入一颗树的程序。

a）在括号里面的表示为上个符号的子节点，如 c , d为b的子节点。a和b为兄弟节点。

b）非递归程序，采用孩子兄弟表示法。

c）难度和括号匹配差不多，只是多了个在进栈出栈时的建树过程。

d）又有nextToken程序。

 

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package cai.tree;import java.io.*;import java.util.*;//(a b(c d) aa (bb cc dd) ee(ff ( gg (h i j))))class BitNode<E>{ public E data; public BitNode<E> left , right; public BitNode(E data){ this.data = data; left = null; right = null; }}class TableToTree{ private String tableString; private Stack<BitNode<String>> theStack; private BitNode<String> root; private int pos; public TableToTree(){ theStack = new Stack<BitNode<String>>(); } private String nextToken(){ if(pos >= tableString.length()){ return null; } char c = tableString.charAt(pos); while(c == ' '){ //去掉空格 pos++; if(pos >= tableString.length()){ return null; }else{ c = tableString.charAt(pos); } } if(Character.isLetter(c)){ StringBuilder strBuilder = new StringBuilder(); do{ strBuilder.append(c); if(pos + 1 == tableString.length()){ pos++; break; } c = tableString.charAt(++pos); }while(Character.isLetterOrDigit(c)); return strBuilder.toString(); }else{ pos++; return c + ""; } } public void toProcess(String tableString){ pos = 0; this.tableString = tableString; theStack.clear(); root = new BitNode<String>("root"); theStack.push(root); String token ; while((token = nextToken()) != null){ if(token.equals("(")){ BitNode<String> opNode = new BitNode<String>("("); String firstChild = nextToken(); BitNode<String> firstNode = new BitNode<String>(firstChild); BitNode<String> parNode = theStack.peek(); parNode.left = firstNode; theStack.push(opNode); theStack.push(firstNode); // System.out.println(theStack.size() + "1111111"); System.out.println(parNode.data + " 's first child " + firstNode.data); }else if(token.equals(")")){ String popString = null; do{ popString = theStack.pop().data; // System.out.println(popString + " dddddddddddd"); }while(!popString.equals("(")); //System.out.println(theStack.size() + "222222222"); }else{ BitNode<String> newNode = new BitNode<String>(token); BitNode<String> sblingNode = theStack.peek(); sblingNode.right = newNode; System.out.println(sblingNode.data + " 's sbling " + newNode.data); theStack.push(newNode); // System.out.println(theStack.size() + "33333333"); } } }}class TableToTreeTest{ public static void main(String[] args){ TableToTree theProcessor = new TableToTree(); theProcessor.toProcess("(a b(c d) aa (bb cc dd) ee(ff ( gg (h i j))))"); } }