-
Notifications
You must be signed in to change notification settings - Fork 0
/
BinaryTreeLevelOrderTraversal.cpp
87 lines (75 loc) · 1.87 KB
/
BinaryTreeLevelOrderTraversal.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
/*
Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).
For example:
Given binary tree {3,9,20,#,#,15,7},
3
/ \
9 20
/ \
15 7
return its level order traversal as:
[
[3],
[9,20],
[15,7]
]
*/
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
#include <iostream>
#include <vector>
using std::vector;
struct TreeNode
{
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
class Solution {
public:
vector<vector<int>> levelOrder(TreeNode* root) {
vector<vector<TreeNode*>> levelNode;
vector<TreeNode*> thislevel;
vector<vector<int>> result;
if(root == NULL){
return result;
}
//initialize
vector<TreeNode*> first;
first.push_back(root);
levelNode.push_back(first);
vector<int> firstResult;
firstResult.push_back(root -> val);
result.push_back(firstResult);
while(true){
thislevel = *(-- levelNode.end());
vector<TreeNode*> nextlevel;
vector<int> thisResult;
for(vector<TreeNode*> :: iterator i = thislevel.begin(); i != thislevel.end(); i ++){
if((*i) -> left != NULL){
nextlevel.push_back((*i) -> left);
thisResult.push_back((*i) -> left -> val);
}
if((*i) -> right != NULL){
nextlevel.push_back((*i) -> right);
thisResult.push_back((*i) -> right -> val);
}
}
if(nextlevel.size() == 0){
break;
} else{
levelNode.push_back(nextlevel);
result.push_back(thisResult);
}
}
return result;
}
};