添加 0112.路径总和、0113.路径总和 II Swift 版本

problems/0112.路径总和.md

@@ -766,7 +766,124 @@ let pathSum = function(root, targetSum) {
 };
 ```
 
+## Swift
 
+0112.路径总和
+
+**递归**
+```swift
+func hasPathSum(_ root: TreeNode?, _ targetSum: Int) -> Bool {
+    guard let root = root else {
+        return false
+    }
+    
+    return traversal(root, targetSum - root.val)
+}
+
+func traversal(_ cur: TreeNode?, _ count: Int) -> Bool {
+    if cur?.left == nil && cur?.right == nil && count == 0 {
+        return true
+    }
+    
+    if cur?.left == nil && cur?.right == nil {
+        return false
+    }
+    
+    if let leftNode = cur?.left {
+        if traversal(leftNode, count - leftNode.val) {
+            return true
+        }
+    }
+    
+    if let rightNode = cur?.right {
+        if traversal(rightNode, count - rightNode.val) {
+            return true
+        }
+    }
+    
+    return false
+}
+```
+**迭代**
+```swift
+func hasPathSum(_ root: TreeNode?, _ targetSum: Int) -> Bool {
+    guard let root = root else {
+        return false
+    }
+    
+    var stack = Array<(TreeNode, Int)>()
+    stack.append((root, root.val))
+    
+    while !stack.isEmpty {
+        let node = stack.removeLast()
+        
+        if node.0.left == nil && node.0.right == nil && targetSum == node.1 {
+            return true
+        }
+        
+        if let rightNode = node.0.right {
+            stack.append((rightNode, node.1 + rightNode.val))
+        }
+        
+        if let leftNode = node.0.left {
+            stack.append((leftNode, node.1 + leftNode.val))
+        }
+    }
+    
+    return false
+}
+```
+
+0113.路径总和 II
+
+**递归**
+
+```swift
+var result = [[Int]]()
+var path = [Int]()
+func pathSum(_ root: TreeNode?, _ targetSum: Int) -> [[Int]] {
+    result.removeAll()
+    path.removeAll()
+    guard let root = root else {
+        return result
+    }
+    path.append(root.val)
+    traversal(root, count: targetSum - root.val)
+    return result
+
+}
+
+func traversal(_ cur: TreeNode?, count: Int) {
+    var count = count
+    // 遇到了叶子节点且找到了和为targetSum的路径
+    if cur?.left == nil && cur?.right == nil && count == 0 {
+        result.append(path)
+        return
+    }
+    
+    // 遇到叶子节点而没有找到合适的边，直接返回
+    if cur?.left == nil && cur?.right == nil{
+        return
+    }
+    
+    if let leftNode = cur?.left {
+        path.append(leftNode.val)
+        count -= leftNode.val
+        traversal(leftNode, count: count)// 递归
+        count += leftNode.val// 回溯
+        path.removeLast()// 回溯
+    }
+    
+    if let rightNode = cur?.right {
+        path.append(rightNode.val)
+        count -= rightNode.val
+        traversal(rightNode, count: count)// 递归
+        count += rightNode.val// 回溯
+        path.removeLast()// 回溯
+    }
+    return
+}
+```