一般來說，二叉樹的遍歷是C++程序員在面試中經常考察的，其實前中后三種順序的遍歷都大同小異，自己模擬兩個棧用筆畫畫是不難寫出代碼的。現舉一個非遞歸遍歷的方法如下，供大家參考。
具體代碼如下：
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class Solution {public: vector<int> preorderTraversal(TreeNode *root) { vector<int> out; stack<TreeNode*> s; s.push(root); while(!s.empty() && root){ TreeNode *node = s.top(); out.push_back(node->val); s.pop(); if(node->right) s.push(node->right); if(node->left) s.push(node->left); } return out; } vector<int> inorderTraversal(TreeNode *root) { stack<TreeNode *> s; vector<int> out; TreeNode *node = root; bool done = false; while(!done){ if(node){ s.push(node); node = node->left; }else { if(s.empty()) done = true; else{ node = s.top(); s.pop(); out.push_back(node->val); node = node->right; } } } return out; } vector<int> postorderTraversal(TreeNode *root) { vector<int> out; stack<TreeNode*> s; TreeNode* node = root; s.push(node); while(!s.empty()&&node){ node = s.top(); out.push_back(node->val); s.pop(); if(node->left) s.push(node->left); if(node->right)s.push(node->right); } reverse(out.begin(),out.end()); return out; }}; |
希望本文所述對大家的C++算法學習有所幫助。
