考点:
举例让抽象具体化
题目描述:
从上往下打印出二叉树的每个节点,同层节点从左至右打印。
解题:
/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};*/
class Solution {
public:
vector<int> PrintFromTopToBottom(TreeNode* root) {
vector<int> res;
if(!root){
return res;
}
queue<TreeNode *> q;
q.push(root);
while(!q.empty()){
res.push_back(q.front()->val);
if(q.front()->left){
q.push(q.front()->left);
}
if(q.front()->right){
q.push(q.front()->right);
}
q.pop();
}
return res;
}
};
/*
bfs.借助队列来实现
*/