invert binary tree solved

invert-binary-tree/mintheon.java

@@ -0,0 +1,52 @@
+import java.util.ArrayDeque;
+import java.util.Queue;
+
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+//시간복잡도: O(n)
+//공간복잡도: O(n)
+class Solution {
+  public TreeNode invertTree(TreeNode root) {
+    if(root == null) {
+      return root;
+    }
+
+    Queue<TreeNode> queue = new ArrayDeque<>();
+    queue.add(root);
+
+    while(!queue.isEmpty()) {
+      TreeNode cur = queue.poll();
+
+      if(cur == null) {
+        continue;
+      }
+
+      TreeNode temp = cur.left;
+      cur.left = cur.right;
+      cur.right = temp;
+
+      if(cur.left != null) {
+        queue.add(cur.left);
+      }
+
+      if(cur.right != null) {
+        queue.add(cur.right);
+      }
+    }
+
+    return root;
+  }
+}