Add solution 0665、0669、1423、1463、1579

leetcode/0669.Trim-a-Binary-Search-Tree/669. Trim a Binary Search Tree.go

@@ -0,0 +1,32 @@
+package leetcode
+
+import (
+	"github.com/halfrost/LeetCode-Go/structures"
+)
+
+// TreeNode define
+type TreeNode = structures.TreeNode
+
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+
+func trimBST(root *TreeNode, low int, high int) *TreeNode {
+	if root == nil {
+		return root
+	}
+	if root.Val > high {
+		return trimBST(root.Left, low, high)
+	}
+	if root.Val < low {
+		return trimBST(root.Right, low, high)
+	}
+	root.Left = trimBST(root.Left, low, high)
+	root.Right = trimBST(root.Right, low, high)
+	return root
+}

leetcode/0669.Trim-a-Binary-Search-Tree/669. Trim a Binary Search Tree_test.go

@@ -0,0 +1,68 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/halfrost/LeetCode-Go/structures"
+)
+
+type question669 struct {
+	para669
+	ans669
+}
+
+// para 是参数
+// one 代表第一个参数
+type para669 struct {
+	one  []int
+	low  int
+	high int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans669 struct {
+	one []int
+}
+
+func Test_Problem669(t *testing.T) {
+
+	qs := []question669{
+
+		{
+			para669{[]int{1, 0, 2}, 1, 2},
+			ans669{[]int{1, structures.NULL, 2}},
+		},
+
+		{
+			para669{[]int{3, 0, 4, structures.NULL, 2, structures.NULL, structures.NULL, 1}, 1, 3},
+			ans669{[]int{3, 2, structures.NULL, 1}},
+		},
+
+		{
+			para669{[]int{1}, 1, 2},
+			ans669{[]int{1}},
+		},
+
+		{
+			para669{[]int{1, structures.NULL, 2}, 1, 3},
+			ans669{[]int{1, structures.NULL, 2}},
+		},
+
+		{
+			para669{[]int{1, structures.NULL, 2}, 2, 4},
+			ans669{[]int{2}},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 669------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans669, q.para669
+		fmt.Printf("【input】:%v      ", p)
+		root := structures.Ints2TreeNode(p.one)
+		fmt.Printf("【output】:%v      \n", structures.Tree2ints(trimBST(root, p.low, p.high)))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/0669.Trim-a-Binary-Search-Tree/README.md

@@ -0,0 +1,100 @@
+# [669. Trim a Binary Search Tree](https://leetcode.com/problems/trim-a-binary-search-tree/)
+
+
+## 题目
+
+Given the `root` of a binary search tree and the lowest and highest boundaries as `low` and `high`, trim the tree so that all its elements lies in `[low, high]`. Trimming the tree should **not** change the relative structure of the elements that will remain in the tree (i.e., any node's descendant should remain a descendant). It can be proven that there is a **unique answer**.
+
+Return *the root of the trimmed binary search tree*. Note that the root may change depending on the given bounds.
+
+**Example 1:**
+
+![https://assets.leetcode.com/uploads/2020/09/09/trim1.jpg](https://assets.leetcode.com/uploads/2020/09/09/trim1.jpg)
+
+```
+Input: root = [1,0,2], low = 1, high = 2
+Output: [1,null,2]
+```
+
+**Example 2:**
+
+![https://assets.leetcode.com/uploads/2020/09/09/trim2.jpg](https://assets.leetcode.com/uploads/2020/09/09/trim2.jpg)
+
+```
+Input: root = [3,0,4,null,2,null,null,1], low = 1, high = 3
+Output: [3,2,null,1]
+```
+
+**Example 3:**
+
+```
+Input: root = [1], low = 1, high = 2
+Output: [1]
+```
+
+**Example 4:**
+
+```
+Input: root = [1,null,2], low = 1, high = 3
+Output: [1,null,2]
+```
+
+**Example 5:**
+
+```
+Input: root = [1,null,2], low = 2, high = 4
+Output: [2]
+```
+
+**Constraints:**
+
+- The number of nodes in the tree in the range `[1, 10^4]`.
+- `0 <= Node.val <= 10^4`
+- The value of each node in the tree is **unique**.
+- `root` is guaranteed to be a valid binary search tree.
+- `0 <= low <= high <= 10^4`
+
+## 题目大意
+
+给你二叉搜索树的根节点 root ，同时给定最小边界low 和最大边界 high。通过修剪二叉搜索树，使得所有节点的值在[low, high]中。修剪树不应该改变保留在树中的元素的相对结构（即，如果没有被移除，原有的父代子代关系都应当保留）。 可以证明，存在唯一的答案。所以结果应当返回修剪好的二叉搜索树的新的根节点。注意，根节点可能会根据给定的边界发生改变。
+
+## 解题思路
+
+- 这一题考察二叉搜索树中的递归遍历。递归遍历二叉搜索树每个结点，根据有序性，当前结点如果比 high 大，那么当前结点的右子树全部修剪掉，再递归修剪左子树；当前结点如果比 low 小，那么当前结点的左子树全部修剪掉，再递归修剪右子树。处理完越界的情况，剩下的情况都在区间内，分别递归修剪左子树和右子树即可。
+
+## 代码
+
+```go
+package leetcode
+
+import (
+	"github.com/halfrost/LeetCode-Go/structures"
+)
+
+// TreeNode define
+type TreeNode = structures.TreeNode
+
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+
+func trimBST(root *TreeNode, low int, high int) *TreeNode {
+	if root == nil {
+		return root
+	}
+	if root.Val > high {
+		return trimBST(root.Left, low, high)
+	}
+	if root.Val < low {
+		return trimBST(root.Right, low, high)
+	}
+	root.Left = trimBST(root.Left, low, high)
+	root.Right = trimBST(root.Right, low, high)
+	return root
+}
+```