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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;
}
};
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