Leetcode_102
層序遍歷
#include <iostream>
#include <vector>
#include <queue>
using namespace std;
struct TreeNode
{
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x):val(x),left(NULL),right(NULL) {}
};
vector<vector<int>> levelOrder(TreeNode* root) {
vector<vector<int>> res;
if(root==NULL)
return res;
queue<pair<TreeNode*,int>> q;
q.push(make_pair(root,0));
while(!q.empty())
{
TreeNode *node = q.front().first;
int level = q.front().second;
q.pop();
if(level == res.size())
res.push_back(vector<int>());
res[level].push_back(node->val);
if(node->left)
q.push(make_pair(node->left,level+1));
if(node->right)
q.push(make_pair(node->right,level+1));
}
return res;
}
