#include<iostream> #include<stack> typedef struct node { int data; struct node*leftptr; struct node*rightptr; }treenode; void initdata(treenode *head) { head->data = 30; head->leftptr = (treenode*)malloc(sizeof(treenode)); memset(head->leftptr, 0, sizeof(treenode)); head->leftptr->data = 20; head->rightptr = (treenode*)malloc(sizeof(treenode)); memset(head->rightptr, 0, sizeof(treenode)); head->rightptr->data = 23; head->leftptr->leftptr = (treenode*)malloc(sizeof(treenode)); memset(head->leftptr->leftptr, 0, sizeof(treenode)); head->leftptr->leftptr->data = 16; head->leftptr->rightptr = (treenode*)malloc(sizeof(treenode)); memset(head->leftptr->rightptr, 0, sizeof(treenode)); head->leftptr->rightptr->data = 17; head->rightptr->leftptr = (treenode*)malloc(sizeof(treenode)); memset(head->rightptr->leftptr, 0, sizeof(treenode)); head->rightptr->leftptr->data = 29; head->rightptr->rightptr = (treenode*)malloc(sizeof(treenode)); memset(head->rightptr->rightptr, 0, sizeof(treenode)); head->rightptr->rightptr->data = 33; } void reserverfirst(treenode*head) { if (head == NULL) { return; } std::cout << head->data << std::endl; if (head->leftptr!=NULL) reserverfirst(head->leftptr); if (head->rightptr!=NULL) reserverfirst(head->rightptr); } std::stack<treenode*>ptrtree; void reserveusestack(treenode*head) { if (head == NULL) { return; } if (head->rightptr != NULL) { ptrtree.push(head->rightptr); } } #if 0 void preOrder2(treenode* pRoot) { std::stack<treenode*> s; treenode *p = pRoot; if (pRoot == NULL) return; while (p != NULL || !s.empty()) { while (p != NULL) { std::cout << p->data << " "; s.push(p); p = p->leftptr; } if (!s.empty()) { p = s.top(); s.pop(); p = p->rightptr; } } } #endif int main() { treenode*head = (treenode*)malloc(sizeof(treenode)); memset(head, 0, sizeof(treenode)); initdata(head); //reserverfirst(head); preOrder2(head); return 0; }