第五章 树与二叉树

4. 层次遍历 ---- BUG FREE

public void levelTraverse(){
        BiTreeNode T = root;
        if(T != null){
            LinkQueue Q = new LinkQueue();
            Q.offer(T);
            while(! Q.isEmpty()){
                T = (BiTreeNode)Q.peek();
                System.out.print(T.data);
                Q.poll();
                if(T.lchild != null){
                    Q.offer(T.lchild);
                }
                if(T.rchild != null){
                    Q.offer(T.rchild);
                }
            }
        }
    }

3. 后根遍历 ----　NOT BUG FREE

    public void postRootTraverse(){
        BiTreeNode T = root;
        if(T != null){
            LinkStack S = new LinkStack();
            S.push(T);
            boolean flag;
            BiTreeNode p = null;
            while(!S.isEmpty()){
                while(S.peek() != null){
                    T = (BiTreeNode)S.peek();
                    S.push(T.lchild);
                }
                S.pop();
                while(!S.isEmpty()){
                    T = (BiTreeNode)S.peek();
                    if(T.rchild == null || T.rchild == P){
                        System.out.print(T.data);
                        S.pop();
                        p = T;
                        flag = true;
                    }else{
                        S.push(T.rchild);
                        flag = false;
                    }
                    if(! false)
                        break;
                }
            }
        }
    }

2. 中根遍历 ---- NOT BUG FREE

    public void inRootTraverse(){
        BiTreeNode T = root;
        if(T != null){
            LinkStack S = new LinkStack();
            S.push(T);
            while( ! S.isEmpty()){
                while(S.seek() != null){
                    S.push(((BiTreeNode)S.seek()).lchild);
                }
                S.pop();
                if(! S.isEmpty()){
                    T = (BiTreeNode)S.pop();
                    System.out.print(T.data);
                    S.push(T.lchild);
                }
                /*if(S.seek().rchild != null){
                    T = S.pop();
                    System.out.print(T);
                    S.push(T.rchild);
                }*/
            }
        }
    }

1. 递归算法与非递归算法实现二叉树的遍历（先根遍历） ---- NOT BUG FREE

public class BiTree{
    private BiTreeNode root;
    public BiTree(){
        this.root = null;
    }
    public BiTree(BiTreeNode root){
        this.root = root
    }
    //遍历法
    public void preRootTraverse(BiTreeNode T){
        if(T != null){
            System.out.printIn(T.data);
            preRootTraverse(T.lchild);
            preRootTraverse(T.rchild);
        }
    }
    //非遍历法**创建栈对象，根节点入栈；栈非空时，栈顶弹出并访问结点；
    //对当前访问结点的非空左孩子结点相继依次访问，并将当前访问结点的非空右孩子结点压入栈内。
    //循环执行，直到栈空。
    public void preRootTraverse(){
        BiTreeNode T = root;
        if(T != null){
            LinkStack s = new LinkStack();
            s.push(T);
            while(!s.isEmpty){
                T = (BiTreeNode)s.pop();
                System.out.print(T.data);
                /*while(T.lchild != null){
                    T = T.lchild;
                    System.out.print(T.data);
                    if(T.rchild != null){
                        s.push(T.rchild)
                    }
                }*/
                while(T != null){
                    if(T.lchild != null){
                        System.out.print(T.lchild.data);
                    }
                    if(T.rchild != null){
                        s.push(T.rchild);
                    }
                    T = T.lchild;
                }
            }
        }
    }
}