二叉树的非递归遍历(前、中、后)

前序:

void PreorderNoR(Node *root){
	stack s;
	Node *cur = root;
	while(!s.empty()&&cur!=NULL){
		while(cur!=NULL){
			printf("%c",cur->value);
			s.push(cur);
			cur = cur->left;
		}
		Node *top = s.top();
		s.pop();
		
		cur = top->right;
	}
	printf("\n");
}

中序:

void InorderNoR(Node *root){
	stack  s;
	Node *cur = root;
	
	while(!s.empty()||cur!=NULL){
		while(cur!=NULL){
			s.push(cur);
			cur = cur->left;
		}
		Node *top = s.top();
		s.pop();
		printf("%c",top->value);
		cur = top->right;
	}
	printf("\n");
}

后序:

void Postorder(Node *root){
	stack s;
	Node *cur = root;
	Node *last = NULL;//上一次被完整遍历完的树的根结点
	
	while(!s.empty()||cur!=NULL){
		while(cur!=NULL)
		{
			s.push(cur);
			cur = cur->left;
		}
		Node *top = s.top();
		if(top->right == NULL){
			printf("%c",top->value);
			s.pop();
			last = top;
		}
		else if(top->right == last){
			printf("%c",top->value);
			s.pop();
			last = top;
		}
		else{
			cur = top->right;
		}
		cur = top->right;
	}
}

 

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