[劍指offer] 59. 按之字形順序列印二叉樹
阿新 • • 發佈：2019-01-09
題目描述
請實現一個函式按照之字形列印二叉樹，即第一行按照從左到右的順序列印，第二層按照從右至左的順序列印，第三行按照從左到右的順序列印，其他行以此類推思路： 用兩個棧或佇列去儲存，用一個變量表示方向，根據不同方向存取順序不同。
class Solution { public: vector<vector<int>> Print(TreeNode *pRoot) { vector<vector<int>> res; if (pRoot == NULL)return res; int direct = 1; stack<TreeNode *> staO; stack<TreeNode *> staE; TreeNode *cur; staO.push(pRoot); while (!staO.empty() || !staE.empty()) { vector<int> temp; if (direct % 2 != 0) {while (!staO.empty()) { cur = staO.top(); staO.pop(); temp.push_back(cur->val); if (cur->left != NULL) staE.push(cur->left); if (cur->right != NULL) staE.push(cur->right); } res.push_back(temp); direct = 2; } else { while (!staE.empty()) { cur = staE.top(); staE.pop(); temp.push_back(cur->val); if (cur->right != NULL) staO.push(cur->right); if (cur->left != NULL) staO.push(cur->left); } res.push_back(temp); direct = 1; } } return res; } };