二叉樹前序 ABDECF

http://baike.baidu.com/link?url=WzF8_CzDS20NTsEFJX1nhISqpnWTEoHhCuPQMMHCC_qjO89k6cqtfJkCf_9ndA4lJJyXMA5oWJiKTcPG61Z6ta#2_3

二叉樹定義


    
publicclassTreeNode{
intval;
TreeNodeleft;
TreeNoderight;
TreeNode(intx){
val=x;
}
}
遞歸實現
publicvoidpreOrder(TreeNodebiTree){
System.out.printf(biTree.val+"");
TreeNodeleftTree=biTree.left;
if(leftTree!=null){
preOrder(leftTree);
}
TreeNoderightTree=biTree.right;
if(rightTree!=null){
preOrder(rightTree);
}
}

非遞歸實現
    
publicvoidpreOrder(TreeNodebiTree){
Stack<TreeNode>stack=newStack<TreeNode>();
while(biTree!=null||!stack.isEmpty()){
while(node!=null){
    System.out.print(biTree.value+",");
    stack.push(biTree);
    biTree=biTree.left;
    }
    if(!stack.isEmpty()){
    biTree=stack.pop();
    biTree=biTree.right;
    }
}
}