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-rw-r--r--other/binary_tree_zigzag.cpp36
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+// 103. Binary Tree Zigzag Level Order Traversal
+#include "leetcode.h"
+// given the 'root' of a binary tree, return the zigzag level order traversal of
+// its nodes' values (ie. from left to right, then right to left for the next
+// level)
+
+class Solution {
+public:
+ vvd zigzagLevelOrder(TreeNode *root) {
+ if (!root)
+ return {};
+ queue<TreeNode *> q;
+ vvd ans;
+ q.push(root);
+ int level = 0;
+ while (!q.empty()) {
+ int sz = q.size();
+ vector<int> curr(sz);
+ for (int i = 0; i < sz; i++) {
+ TreeNode *tmp = q.front();
+ q.pop();
+ if (level == 0)
+ curr[i] = tmp->val;
+ else
+ curr[sz - i - 1] = tmp->val;
+ if (tmp->left)
+ q.push(tmp->left);
+ if (tmp->right)
+ q.push(tmp->right);
+ }
+ ans.push_back(curr);
+ level = !level;
+ }
+ return ans;
+ }
+};