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| struct TreeNode {
int val;
TreeNode *left;
TreeNode *right;
TreeNode()
: val(0)
, left(nullptr)
, right(nullptr)
{
}
TreeNode(int x)
: val(x)
, left(nullptr)
, right(nullptr)
{
}
TreeNode(int x, TreeNode *left, TreeNode *right)
: val(x)
, left(left)
, right(right)
{
}
};
#include <vector>
#include <queue>
#include <algorithm>
using std::vector;
using std::queue;
class Solution {
public:
vector<vector<int> > zigzagLevelOrder(TreeNode *root)
{
int i, n;
queue<TreeNode *> que;
vector<vector<int> > res;
bool reverse = false;
TreeNode *p;
if (root == nullptr) {
return res;
}
que.push(root);
while (!que.empty()) {
n = que.size();
vector<int> vec(n);
for (i = 0; i < n; i++) {
p = que.front();
que.pop();
vec[i] = p->val;
if (p->left) {
que.push(p->left);
}
if (p->right) {
que.push(p->right);
}
}
if (reverse) {
std::reverse(vec.begin(), vec.end());
}
res.push_back(vec);
reverse = !reverse;
}
return res;
}
};
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