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feat: add solutions to lc/lcof2 problems
lc No.0515 & lcof2 No.044. Find Largest Value in Each Tree Row
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11 files changed

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-199
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11 files changed

+341
-199
lines changed

‎lcof2/剑指 Offer II 044. 二叉树每层的最大值/README.md‎

Lines changed: 76 additions & 39 deletions
Original file line numberDiff line numberDiff line change
@@ -94,8 +94,8 @@ class Solution:
9494
def largestValues(self, root: TreeNode) -> List[int]:
9595
if root is None:
9696
return []
97-
q = collections.deque([root])
98-
res = []
97+
q = deque([root])
98+
ans = []
9999
while q:
100100
n = len(q)
101101
t = float('-inf')
@@ -106,8 +106,8 @@ class Solution:
106106
q.append(node.left)
107107
if node.right:
108108
q.append(node.right)
109-
res.append(t)
110-
return res
109+
ans.append(t)
110+
return ans
111111
```
112112

113113
### **Java**
@@ -137,7 +137,7 @@ class Solution {
137137
}
138138
Deque<TreeNode> q = new ArrayDeque<>();
139139
q.offer(root);
140-
List<Integer> res = new ArrayList<>();
140+
List<Integer> ans = new ArrayList<>();
141141
while (!q.isEmpty()) {
142142
int t = Integer.MIN_VALUE;
143143
for (int i = 0, n = q.size(); i < n; ++i) {
@@ -150,59 +150,96 @@ class Solution {
150150
q.offer(node.right);
151151
}
152152
}
153-
res.add(t);
153+
ans.add(t);
154154
}
155-
return res;
155+
return ans;
156156
}
157157
}
158158
```
159159

160160
### **C++**
161161

162162
```cpp
163+
/**
164+
* Definition for a binary tree node.
165+
* struct TreeNode {
166+
* int val;
167+
* TreeNode *left;
168+
* TreeNode *right;
169+
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
170+
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
171+
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
172+
* };
173+
*/
163174
class Solution {
164175
public:
165176
vector<int> largestValues(TreeNode* root) {
166-
vector<int> res;
167-
if (!root)
168-
{
169-
return res;
170-
}
171-
172-
deque<TreeNode *> deq;
173-
deq.push_back(root);
174-
while (!deq.empty())
177+
if (!root) return {};
178+
queue<TreeNode*> q;
179+
vector<int> ans;
180+
q.push(root);
181+
while (!q.empty())
175182
{
176-
int size = deq.size();
177-
int maxnum = INT_MIN;
178-
for (int i = 0; i < size; i++)
183+
int t = INT_MIN;
184+
for (int i = 0, n = q.size(); i < n; ++i)
179185
{
180-
TreeNode *ptr = deq.front();
181-
deq.pop_front();
182-
if (maxnum < ptr->val)
183-
{
184-
maxnum = ptr->val;
185-
}
186-
187-
if (ptr->left)
188-
{
189-
deq.push_back(ptr->left);
190-
}
191-
192-
if (ptr->right)
193-
{
194-
deq.push_back(ptr->right);
195-
}
186+
auto node = q.front();
187+
q.pop();
188+
t = max(t, node->val);
189+
if (node->left) q.push(node->left);
190+
if (node->right) q.push(node->right);
196191
}
197-
198-
res.push_back(maxnum);
192+
ans.push_back(t);
199193
}
200-
201-
return res;
194+
return ans;
202195
}
203196
};
204197
```
205198
199+
### **Go**
200+
201+
```go
202+
/**
203+
* Definition for a binary tree node.
204+
* type TreeNode struct {
205+
* Val int
206+
* Left *TreeNode
207+
* Right *TreeNode
208+
* }
209+
*/
210+
func largestValues(root *TreeNode) []int {
211+
var ans []int
212+
if root == nil {
213+
return ans
214+
}
215+
var q = []*TreeNode{root}
216+
for len(q) > 0 {
217+
n := len(q)
218+
t := math.MinInt32
219+
for i := 0; i < n; i++ {
220+
node := q[0]
221+
q = q[1:]
222+
t = max(t, node.Val)
223+
if node.Left != nil {
224+
q = append(q, node.Left)
225+
}
226+
if node.Right != nil {
227+
q = append(q, node.Right)
228+
}
229+
}
230+
ans = append(ans, t)
231+
}
232+
return ans
233+
}
234+
235+
func max(a, b int) int {
236+
if a > b {
237+
return a
238+
}
239+
return b
240+
}
241+
```
242+
206243
### **...**
207244

208245
```

‎lcof2/剑指 Offer II 044. 二叉树每层的最大值/Solution.cpp‎

Lines changed: 26 additions & 33 deletions
Original file line numberDiff line numberDiff line change
@@ -1,41 +1,34 @@
1+
/**
2+
* Definition for a binary tree node.
3+
* struct TreeNode {
4+
* int val;
5+
* TreeNode *left;
6+
* TreeNode *right;
7+
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
8+
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
9+
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
10+
* };
11+
*/
112
class Solution {
213
public:
3-
vector<int> largestValues(TreeNode *root) {
4-
vector<int> res;
5-
if (!root)
14+
vector<int> largestValues(TreeNode* root) {
15+
if (!root) return {};
16+
queue<TreeNode*> q;
17+
vector<int> ans;
18+
q.push(root);
19+
while (!q.empty())
620
{
7-
return res;
8-
}
9-
10-
deque<TreeNode *> deq;
11-
deq.push_back(root);
12-
while (!deq.empty())
13-
{
14-
int size = deq.size();
15-
int maxnum = INT_MIN;
16-
for (int i = 0; i < size; i++)
21+
int t = INT_MIN;
22+
for (int i = 0, n = q.size(); i < n; ++i)
1723
{
18-
TreeNode *ptr = deq.front();
19-
deq.pop_front();
20-
if (maxnum < ptr->val)
21-
{
22-
maxnum = ptr->val;
23-
}
24-
25-
if (ptr->left)
26-
{
27-
deq.push_back(ptr->left);
28-
}
29-
30-
if (ptr->right)
31-
{
32-
deq.push_back(ptr->right);
33-
}
24+
auto node = q.front();
25+
q.pop();
26+
t = max(t, node->val);
27+
if (node->left) q.push(node->left);
28+
if (node->right) q.push(node->right);
3429
}
35-
36-
res.push_back(maxnum);
30+
ans.push_back(t);
3731
}
38-
39-
return res;
32+
return ans;
4033
}
4134
};

‎lcof2/剑指 Offer II 044. 二叉树每层的最大值/Solution.go‎

Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,39 @@
1+
/**
2+
* Definition for a binary tree node.
3+
* type TreeNode struct {
4+
* Val int
5+
* Left *TreeNode
6+
* Right *TreeNode
7+
* }
8+
*/
9+
func largestValues(root *TreeNode) []int {
10+
var ans []int
11+
if root == nil {
12+
return ans
13+
}
14+
var q = []*TreeNode{root}
15+
for len(q) > 0 {
16+
n := len(q)
17+
t := math.MinInt32
18+
for i := 0; i < n; i++ {
19+
node := q[0]
20+
q = q[1:]
21+
t = max(t, node.Val)
22+
if node.Left != nil {
23+
q = append(q, node.Left)
24+
}
25+
if node.Right != nil {
26+
q = append(q, node.Right)
27+
}
28+
}
29+
ans = append(ans, t)
30+
}
31+
return ans
32+
}
33+
34+
func max(a, b int) int {
35+
if a > b {
36+
return a
37+
}
38+
return b
39+
}

‎lcof2/剑指 Offer II 044. 二叉树每层的最大值/Solution.java‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -20,7 +20,7 @@ public List<Integer> largestValues(TreeNode root) {
2020
}
2121
Deque<TreeNode> q = new ArrayDeque<>();
2222
q.offer(root);
23-
List<Integer> res = new ArrayList<>();
23+
List<Integer> ans = new ArrayList<>();
2424
while (!q.isEmpty()) {
2525
int t = Integer.MIN_VALUE;
2626
for (int i = 0, n = q.size(); i < n; ++i) {
@@ -33,8 +33,8 @@ public List<Integer> largestValues(TreeNode root) {
3333
q.offer(node.right);
3434
}
3535
}
36-
res.add(t);
36+
ans.add(t);
3737
}
38-
return res;
38+
return ans;
3939
}
4040
}

‎lcof2/剑指 Offer II 044. 二叉树每层的最大值/Solution.py‎

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -8,8 +8,8 @@ class Solution:
88
def largestValues(self, root: TreeNode) -> List[int]:
99
if root is None:
1010
return []
11-
q = collections.deque([root])
12-
res = []
11+
q = deque([root])
12+
ans = []
1313
while q:
1414
n = len(q)
1515
t = float('-inf')
@@ -20,5 +20,5 @@ def largestValues(self, root: TreeNode) -> List[int]:
2020
q.append(node.left)
2121
if node.right:
2222
q.append(node.right)
23-
res.append(t)
24-
return res
23+
ans.append(t)
24+
return ans

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