diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -54,6 +54,10 @@ LeetCode Problems' Solutions
| # | Title | Solution | Difficulty |
| :-: | - | - | :-: |
+| 1111 | [Maximum Nesting Depth of Two Valid Parentheses Strings](https://leetcode.com/problems/maximum-nesting-depth-of-two-valid-parentheses-strings "有效括号的嵌套深度") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-nesting-depth-of-two-valid-parentheses-strings) | Medium |
+| 1110 | [Delete Nodes And Return Forest](https://leetcode.com/problems/delete-nodes-and-return-forest "删点成林") | [Go](https://github.com/openset/leetcode/tree/master/problems/delete-nodes-and-return-forest) | Medium |
+| 1109 | [Corporate Flight Bookings](https://leetcode.com/problems/corporate-flight-bookings "航班预订统计") | [Go](https://github.com/openset/leetcode/tree/master/problems/corporate-flight-bookings) | Medium |
+| 1108 | [Defanging an IP Address](https://leetcode.com/problems/defanging-an-ip-address "IP 地址无效化") | [Go](https://github.com/openset/leetcode/tree/master/problems/defanging-an-ip-address) | Easy |
| 1107 | [New Users Daily Count](https://leetcode.com/problems/new-users-daily-count) 🔒 | [MySQL](https://github.com/openset/leetcode/tree/master/problems/new-users-daily-count) | Medium |
| 1106 | [Parsing A Boolean Expression](https://leetcode.com/problems/parsing-a-boolean-expression "解析布尔表达式") | [Go](https://github.com/openset/leetcode/tree/master/problems/parsing-a-boolean-expression) | Hard |
| 1105 | [Filling Bookcase Shelves](https://leetcode.com/problems/filling-bookcase-shelves "填充书架") | [Go](https://github.com/openset/leetcode/tree/master/problems/filling-bookcase-shelves) | Medium |
diff --git a/problems/corporate-flight-bookings/README.md b/problems/corporate-flight-bookings/README.md
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+
+
+
+
+
+
+
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/defanging-an-ip-address "Defanging an IP Address")
+
+[Next >](https://github.com/openset/leetcode/tree/master/problems/delete-nodes-and-return-forest "Delete Nodes And Return Forest")
+
+## 1109. Corporate Flight Bookings (Medium)
+
+There are n flights, and they are labeled from 1 to n.
+
+We have a list of flight bookings. The i-th booking bookings[i] = [i, j, k] means that we booked k seats from flights labeled i to j inclusive.
+
+Return an array answer of length n, representing the number of seats booked on each flight in order of their label.
+
+
+Example 1:
+
+
+Input: bookings = [[1,2,10],[2,3,20],[2,5,25]], n = 5
+Output: [10,55,45,25,25]
+
+
+
+Constraints:
+
+
+ 1 <= bookings.length <= 200001 <= bookings[i][0] <= bookings[i][1] <= n <= 200001 <= bookings[i][2] <= 10000
diff --git a/problems/defanging-an-ip-address/README.md b/problems/defanging-an-ip-address/README.md
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+
+
+
+
+
+
+
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/new-users-daily-count "New Users Daily Count")
+
+[Next >](https://github.com/openset/leetcode/tree/master/problems/corporate-flight-bookings "Corporate Flight Bookings")
+
+## 1108. Defanging an IP Address (Easy)
+
+Given a valid (IPv4) IP address, return a defanged version of that IP address.
+
+A defanged IP address replaces every period "." with "[.]".
+
+
+Example 1:
+Input: address = "1.1.1.1"
+Output: "1[.]1[.]1[.]1"
+
Example 2:
+Input: address = "255.100.50.0"
+Output: "255[.]100[.]50[.]0"
+
+
+Constraints:
+
+
+ - The given
address is a valid IPv4 address.
+
diff --git a/problems/delete-nodes-and-return-forest/README.md b/problems/delete-nodes-and-return-forest/README.md
new file mode 100644
index 000000000..1fce5e7b0
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+
+
+
+
+
+
+
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/corporate-flight-bookings "Corporate Flight Bookings")
+
+[Next >](https://github.com/openset/leetcode/tree/master/problems/maximum-nesting-depth-of-two-valid-parentheses-strings "Maximum Nesting Depth of Two Valid Parentheses Strings")
+
+## 1110. Delete Nodes And Return Forest (Medium)
+
+Given the root of a binary tree, each node in the tree has a distinct value.
+
+After deleting all nodes with a value in to_delete, we are left with a forest (a disjoint union of trees).
+
+Return the roots of the trees in the remaining forest. You may return the result in any order.
+
+
+Example 1:
+
+
+
+
+Input: root = [1,2,3,4,5,6,7], to_delete = [3,5]
+Output: [[1,2,null,4],[6],[7]]
+
+
+
+Constraints:
+
+
+ - The number of nodes in the given tree is at most
1000.
+ - Each node has a distinct value between
1 and 1000.
+ to_delete.length <= 1000to_delete contains distinct values between 1 and 1000.
diff --git a/problems/maximum-nesting-depth-of-two-valid-parentheses-strings/README.md b/problems/maximum-nesting-depth-of-two-valid-parentheses-strings/README.md
new file mode 100644
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+
+
+
+
+
+
+
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/delete-nodes-and-return-forest "Delete Nodes And Return Forest")
+
+Next >
+
+## 1111. Maximum Nesting Depth of Two Valid Parentheses Strings (Hard)
+
+A string is a valid parentheses string (denoted VPS) if and only if it consists of "(" and ")" characters only, and:
+
+
+ - It is the empty string, or
+ - It can be written as
AB (A concatenated with B), where A and B are VPS's, or
+ - It can be written as
(A), where A is a VPS.
+
+
+We can similarly define the nesting depth depth(S) of any VPS S as follows:
+
+
+ depth("") = 0depth(A + B) = max(depth(A), depth(B)), where A and B are VPS'sdepth("(" + A + ")") = 1 + depth(A), where A is a VPS.
+
+For example, "", "()()", and "()(()())" are VPS's (with nesting depths 0, 1, and 2), and ")(" and "(()" are not VPS's.
+
+
+
+Given a VPS seq, split it into two disjoint subsequences A and B, such that A and B are VPS's (and A.length + B.length = seq.length).
+
+Now choose any such A and B such that max(depth(A), depth(B)) is the minimum possible value.
+
+Return an answer array (of length seq.length) that encodes such a choice of A and B: answer[i] = 0 if seq[i] is part of A, else answer[i] = 1. Note that even though multiple answers may exist, you may return any of them.
+
+
+Example 1:
+
+
+Input: seq = "(()())"
+Output: [0,1,1,1,1,0]
+
+
+Example 2:
+
+
+Input: seq = "()(())()"
+Output: [0,0,0,1,1,0,1,1]
+
+
+
+Constraints:
+
+
+ 1 <= text.size <= 10000
diff --git a/problems/new-users-daily-count/README.md b/problems/new-users-daily-count/README.md
index 5a74fd74f..d9e9a3ad1 100644
--- a/problems/new-users-daily-count/README.md
+++ b/problems/new-users-daily-count/README.md
@@ -7,7 +7,7 @@
[< Previous](https://github.com/openset/leetcode/tree/master/problems/parsing-a-boolean-expression "Parsing A Boolean Expression")
-Next >
+[Next >](https://github.com/openset/leetcode/tree/master/problems/defanging-an-ip-address "Defanging an IP Address")
## 1107. New Users Daily Count (Medium)