- 二叉樹的前序遍歷非遞歸
void PreOrder(TreeNode *root)
{
if(root == NULL)
return;
stack<TreeNode*> s;
s.push(root);
while(!s.empty())
{
TreeNode *ptemp = s.top();
cout << ptemp->val << " ";
s.pop();
if(ptemp->right)
s.push(ptemp->right);
if(ptemp->left)
s.push(ptemp->left);
}
cout <<endl;
}
- 二叉樹的中序遍歷非遞歸
void InOrder(TreeNode *root)
{
if(root == NULL)
return;
stack<TreeNode*> s;
TreeNode *pcur = root;
while(!s.empty()|| pcur )
{
while(pcur)
{
s.push(pcur);
pcur = pcur->left;
} //while循環後,棧頂元素就是最左元素
pcur = s.top();
cout << pcur->val << " ";
s.pop();
pcur = pcur->right;
}
cout <<endl;
}
- 二叉樹的後序遍歷
void PostOrder(TreeNode *root)
{
if(root == NULL)
return ;
TreeNode *pcur = root;
TreeNode *pPre = NULL; //這個指針標記上次訪問的節點。
stack<TreeNode*> s;
while(!s.empty()|| pcur)
{
while(pcur)
{
s.push(pcur);
pcur = pcur->left;
} //找最左子鏈
TreeNode *ptemp = s.top();
if(ptemp->right == NULL || pPre == ptemp->right) //右孩子已經訪問過了,才訪問根節點。
{
pPre = ptemp;
cout << ptemp->val << " ";
s.pop();
}
else
{
pcur = ptemp->right;
}
}
}
- 兩個鏈表求差集
已知集合A和B的元素分別用不含頭結點的單鏈表存儲,函數difference()用於求解集合A與B的差集,並將結果保存在集合A的單鏈表中。例如,若集合A={5,10,20,15,25,30},集合B={5,15,35,25},完成計算後A={10,20,30}。
鏈表結點的結構類型定義如下:
struct node
{
int elem;
node* next;
};
請完成函數void difference(node** LA , node* LB);
void difference(node **LA, node *LB)
{
if(LA == NULL || *LA == NULL || LB == NULL)
return ;
node *pA = *LA;
node *pB = LB;
while(pB != NULL)
{
node *pre = NULL;
node *pcur = pA;
if(pB->elem == pA->elem) //如果b中的元素和a中頭部的元素相等,要修改頭指針,所以單獨拿出來。
{
node *ptemp = pA;
*LA = pA->next;
delete ptemp;
}
while(pcur != NULL) //不是頭部
{
if(pB->elem == pcur->elem)
{
pre->next = pcur->next;
delete pcur;
break;
}
pre = pcur;
pcur = pcur->next;
}
pB = pB->next;
}
}