二叉树的重建——根据先序遍历和中序遍历序列

TreeImpl是二叉树接口类的一个实现类，详细内容见：https://github.com/xlrainy123/algorithms-implement-by-java/blob/master/src/main/java/tree/TreeImpl.java
直接上代码

/**
     * 根据先序遍历和中序遍历序列重建二叉树
     * @param pre
     * @param in
     * @return
     */
    public TreeImpl reConstructBinaryTree(int[] pre, int[] in){
        TreeNode root = reConstructHandler(pre, 0, pre.length-1, in, 0, in.length-1);
        return new TreeImpl(root);
    }

    private TreeNode reConstructHandler(int[] pre, int prelow, int prehigh, int[] in, int inlow, int inhigh){
        if (prelow > prehigh || inlow > inhigh){
            return null;
        }

        TreeNode root = new TreeNode(pre[prelow]);
        for (int i = inlow; i <= inhigh; i++){
            if (in[i] == root.val){
                root.left = reConstructHandler(pre, prelow+1, prelow+i-inlow, in, inlow, i-1);
                root.right = reConstructHandler(pre, prelow+i-inlow+1, prehigh, in, i+1, inhigh);
                break;
            }
        }
        return root;
    }