【数据结构与算法】重建二叉树

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只能根据前序中序或者中序后序重建二叉树，不可能根据前序和后序重建，因为需要中序去划分左右子树。

代码实现

/** * 源码名称：ConstructBT.java  * 日期：2014-09-05 * 程序功能：重建二叉树（前序中序） * 版权：CopyRight@A2BGeek  * 作者：A2BGeek */public class ConstructBT {class Node<T> {T mValue;Node<T> mLeft;Node<T> mRight;public Node(T value, Node<T> left, Node<T> right) {mValue = value;mLeft = left;mRight = right;}}public Node<Character> buildBT(String pre, String mid) {Node<Character> root = null;String lpre, rpre, lmid, rmid;int pos = 0;if (pre.length() == 0 || mid.length() == 0) {return null;} else {root = new Node<Character>(pre.charAt(0), null, null);while (mid.charAt(pos) != root.mValue) {pos++;}// recursive leftlpre = pre.substring(1, pos + 1);lmid = mid.substring(0, pos);root.mLeft = buildBT(lpre, lmid);// recursive rightrpre = pre.substring(pos + 1, pre.length());rmid = mid.substring(pos + 1, mid.length());root.mRight = buildBT(rpre, rmid);}return root;}public void postIterate(Node<Character> root) {if (root == null) {return;} else {postIterate(root.mLeft);postIterate(root.mRight);System.out.print(root.mValue + " ");}}public static void main(String[] args) {ConstructBT bt = new ConstructBT();Node<Character> root = bt.buildBT("12473568", "47215386");bt.postIterate(root);}}

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