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Commit dcc11b6

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feat: add solutions to lcof2 problem: No.045
1 parent 92f9405 commit dcc11b6

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4 files changed

+181
-2
lines changed

4 files changed

+181
-2
lines changed

‎lcof2/剑指 Offer II 045. 二叉树最底层最左边的值/README.md‎

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Original file line numberDiff line numberDiff line change
@@ -46,22 +46,81 @@
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<!-- 这里可写通用的实现逻辑 -->
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"BFS 层次遍历"实现。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
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# self.val = val
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# self.left = left
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# self.right = right
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class Solution:
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def findBottomLeftValue(self, root: TreeNode) -> int:
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d = deque([root])
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ans = -1
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while d:
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n = len(d)
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for i in range(n):
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node = d.popleft()
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if i == 0:
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ans = node.val
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if node.left:
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d.append(node.left)
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if node.right:
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d.append(node.right)
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return ans
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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/**
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* Definition for a binary tree node.
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* public class TreeNode {
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* int val;
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* TreeNode left;
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* TreeNode right;
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* TreeNode() {}
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* TreeNode(int val) { this.val = val; }
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* TreeNode(int val, TreeNode left, TreeNode right) {
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* this.val = val;
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* this.left = left;
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* this.right = right;
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* }
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* }
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*/
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class Solution {
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public int findBottomLeftValue(TreeNode root) {
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Queue<TreeNode> q = new ArrayDeque<>();
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q.offer(root);
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int ans = -1;
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while (!q.isEmpty()) {
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int n = q.size();
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for (int i = 0; i < n; i++) {
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TreeNode node = q.poll();
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if (i == 0) {
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ans = node.val;
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}
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if (node.left != null) {
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q.offer(node.left);
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}
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if (node.right != null) {
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q.offer(node.right);
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}
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}
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}
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return ans;
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}
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}
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```
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### **C++**
@@ -107,6 +166,39 @@ public:
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};
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```
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### **Go**
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```go
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/**
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* Definition for a binary tree node.
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* type TreeNode struct {
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* Val int
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* Left *TreeNode
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* Right *TreeNode
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* }
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*/
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func findBottomLeftValue(root *TreeNode) int {
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q := []*TreeNode{root}
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ans := -1
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for n := len(q); n > 0; n = len(q) {
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for i := 0; i < n; i++ {
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node := q[0]
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q = q[1:]
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if i == 0 {
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ans = node.Val
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}
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if node.Left != nil {
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q = append(q, node.Left)
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}
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if node.Right != nil {
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q = append(q, node.Right)
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}
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}
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}
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return ans
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}
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```
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### **...**
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```
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@@ -0,0 +1,28 @@
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/**
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* Definition for a binary tree node.
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* type TreeNode struct {
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* Val int
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* Left *TreeNode
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* Right *TreeNode
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* }
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*/
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func findBottomLeftValue(root *TreeNode) int {
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q := []*TreeNode{root}
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ans := -1
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for n := len(q); n > 0; n = len(q) {
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for i := 0; i < n; i++ {
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node := q[0]
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q = q[1:]
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if i == 0 {
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ans = node.Val
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}
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if node.Left != nil {
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q = append(q, node.Left)
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}
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if node.Right != nil {
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q = append(q, node.Right)
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}
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}
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}
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return ans
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}
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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,38 @@
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/**
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* Definition for a binary tree node.
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* public class TreeNode {
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* int val;
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* TreeNode left;
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* TreeNode right;
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* TreeNode() {}
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* TreeNode(int val) { this.val = val; }
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* TreeNode(int val, TreeNode left, TreeNode right) {
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* this.val = val;
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* this.left = left;
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* this.right = right;
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* }
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* }
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*/
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class Solution {
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public int findBottomLeftValue(TreeNode root) {
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Queue<TreeNode> q = new ArrayDeque<>();
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q.offer(root);
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int ans = -1;
21+
while (!q.isEmpty()) {
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int n = q.size();
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for (int i = 0; i < n; i++) {
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TreeNode node = q.poll();
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if (i == 0) {
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ans = node.val;
27+
}
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if (node.left != null) {
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q.offer(node.left);
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}
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if (node.right != null) {
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q.offer(node.right);
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}
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}
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}
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return ans;
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}
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}
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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,21 @@
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
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# self.val = val
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# self.left = left
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# self.right = right
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class Solution:
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def findBottomLeftValue(self, root: TreeNode) -> int:
9+
d = deque([root])
10+
ans = -1
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while d:
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n = len(d)
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for i in range(n):
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node = d.popleft()
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if i == 0:
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ans = node.val
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if node.left:
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d.append(node.left)
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if node.right:
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d.append(node.right)
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return ans

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