Merge branch 'main' into patch-1

Author: hyiltiz

images/starcharts.svg

@@ -275,14 +275,14 @@ class Solution {
     func reverseList(_ head: ListNode?) -> ListNode? {
         let dummy = ListNode(0)
         var curr = head
-        
+
         while curr != nil {
             let next = curr?.next
             curr?.next = dummy.next
             dummy.next = curr
             curr = next
         }
-        
+
         return dummy.next
     }
 }

lcof/面试题24. 反转链表/README.md

@@ -330,7 +330,7 @@ class Solution {
         var cur: ListNode? = dummy
         var l1 = l1
         var l2 = l2
-        
+
         while let l1Node = l1, let l2Node = l2 {
             if l1Node.val <= l2Node.val {
                 cur?.next = l1Node
@@ -341,9 +341,9 @@ class Solution {
             }
             cur = cur?.next
         }
-        
+
         cur?.next = l1 ?? l2
-        
+
         return dummy.next
     }
 }

lcof/面试题25. 合并两个排序的链表/README.md

@@ -334,14 +334,14 @@ class Solution {
         guard !matrix.isEmpty && !matrix[0].isEmpty else {
             return []
         }
-        
+
         let m = matrix.count
         let n = matrix[0].count
         var vis = Array(repeating: Array(repeating: false, count: n), count: m)
         var ans = [Int]()
         var i = 0, j = 0, k = 0
         let dirs = [0, 1, 0, -1, 0]
-        
+
         for _ in 0..<m*n {
             ans.append(matrix[i][j])
             vis[i][j] = true
@@ -354,7 +354,7 @@ class Solution {
             i = x
             j = y
         }
-        
+
         return ans
     }
 }

lcof/面试题29. 顺时针打印矩阵/README.md

@@ -215,15 +215,15 @@ class Solution {
     func validateStackSequences(_ pushed: [Int], _ popped: [Int]) -> Bool {
         var stack = [Int]()
         var j = 0
-        
+
         for v in pushed {
             stack.append(v)
             while !stack.isEmpty && stack.last == popped[j] {
                 stack.removeLast()
                 j += 1
             }
         }
-        
+
         return j == pushed.count
     }
 }

lcof/面试题31. 栈的压入、弹出序列/README.md

@@ -399,7 +399,7 @@ public class Solution {
  *     }
  * }
  */
- 
+
 class Solution {
     private var t = [Int]()
     private var ans = [[Int]]()

lcof/面试题34. 二叉树中和为某一值的路径/README.md

@@ -296,17 +296,17 @@ public class Solution {
 *     public var val: Int
 *     public var next: Node?
 *     public var random: Node?
-    
+
 *     public init(_ val: Int) {
 *         self.val = val
 *         self.next = nil
 *         self.random = nil
 *     }
-    
+
 *     public static func == (lhs: Node, rhs: Node) -> Bool {
 *         return lhs === rhs
 *     }
-    
+
 *     public func hash(into hasher: inout Hasher) {
 *         hasher.combine(ObjectIdentifier(self))
 *     }
@@ -319,23 +319,23 @@ class Solution {
         let dummy = Node(0)
         var tail: Node? = dummy
         var cur = head
-        
+
         while cur != nil {
             tail?.next = Node(cur!.val)
             tail = tail?.next
             d[cur!] = tail
             cur = cur?.next
         }
-        
+
         tail = dummy.next
         cur = head
-        
+
         while cur != nil {
             tail?.random = d[cur!.random ?? Node(0)]
             tail = tail?.next
             cur = cur?.next
         }
-        
+
         return dummy.next
     }
 }

lcof/面试题35. 复杂链表的复制/README.md

@@ -283,6 +283,43 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    private var ans: [String] = []
+    private var cs: [Character] = []
+
+    func permutation(_ s: String) -> [String] {
+        cs = Array(s)
+        dfs(0)
+        return ans
+    }
+
+    private func dfs(_ i: Int) {
+        if i == cs.count - 1 {
+            ans.append(String(cs))
+            return
+        }
+        var vis: Set<Character> = []
+        for j in i..<cs.count {
+            if !vis.contains(cs[j]) {
+                vis.insert(cs[j])
+                swap(i, j)
+                dfs(i + 1)
+                swap(i, j)
+            }
+        }
+    }
+
+    private func swap(_ i: Int, _ j: Int) {
+        let t = cs[i]
+        cs[i] = cs[j]
+        cs[j] = t
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof/面试题38. 字符串的排列/README.md

@@ -0,0 +1,32 @@
+class Solution {
+    private var ans: [String] = []
+    private var cs: [Character] = []
+
+    func permutation(_ s: String) -> [String] {
+        cs = Array(s)
+        dfs(0)
+        return ans
+    }
+
+    private func dfs(_ i: Int) {
+        if i == cs.count - 1 {
+            ans.append(String(cs))
+            return
+        }
+        var vis: Set<Character> = []
+        for j in i..<cs.count {
+            if !vis.contains(cs[j]) {
+                vis.insert(cs[j])
+                swap(i, j)
+                dfs(i + 1)
+                swap(i, j)
+            }
+        }
+    }
+
+    private func swap(_ i: Int, _ j: Int) {
+        let t = cs[i]
+        cs[i] = cs[j]
+        cs[j] = t
+    }
+}

lcof/面试题38. 字符串的排列/Solution.swift

@@ -196,6 +196,27 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func majorityElement(_ nums: [Int]) -> Int {
+        var cnt = 0
+        var m = 0
+
+        for v in nums {
+            if cnt == 0 {
+                m = v
+                cnt = 1
+            } else {
+                cnt += (m == v ? 1 : -1)
+            }
+        }
+        return m
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->