111. Minimum Depth of Binary Tree

Author: TBXark

111. Minimum Depth of Binary Tree.md

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+# 111. Minimum Depth of Binary Tree
+
+### 2017-03-16
+
+Given a binary tree, find its minimum depth.
+
+The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.
+
+
+
+# Solution
+
+```swift
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public var val: Int
+ *     public var left: TreeNode?
+ *     public var right: TreeNode?
+ *     public init(_ val: Int) {
+ *         self.val = val
+ *         self.left = nil
+ *         self.right = nil
+ *     }
+ * }
+ */
+class Solution {
+    func minDepth(_ root: TreeNode?) -> Int {
+        guard let r = root else { return 0 }
+        var temp = [root]
+        var deep = 0
+        while temp.count != 0 {
+            deep += 1
+            for _ in 0..<temp.count {
+                guard let n = temp.removeFirst() else { return deep }
+                if n.left == nil && n.right == nil { return deep }
+                if let l = n.left { temp.append(l) } 
+                if let r = n.right { temp.append(r) } 
+            }
+        }
+        return deep
+    }
+}
+```
+