You are given the root of a binary tree with unique values.
In one operation, you can choose any two nodes at the same level and swap their values.
\n\nReturn the minimum number of operations needed to make the values at each level sorted in a strictly increasing order.
\n\nThe level of a node is the number of edges along the path between it and the root node.
\n\n\n
Example 1:
\n![](\"https://assets.leetcode.com/uploads/2022/09/18/image-20220918174006-2.png\")
\n\nInput: root = [1,4,3,7,6,8,5,null,null,null,null,9,null,10]\nOutput: 3\nExplanation:\n- Swap 4 and 3. The 2nd level becomes [3,4].\n- Swap 7 and 5. The 3rd level becomes [5,6,8,7].\n- Swap 8 and 7. The 3rd level becomes [5,6,7,8].\nWe used 3 operations so return 3.\nIt can be proven that 3 is the minimum number of operations needed.\n\n\n
Example 2:
\n![](\"https://assets.leetcode.com/uploads/2022/09/18/image-20220918174026-3.png\")
\n\nInput: root = [1,3,2,7,6,5,4]\nOutput: 3\nExplanation:\n- Swap 3 and 2. The 2nd level becomes [2,3].\n- Swap 7 and 4. The 3rd level becomes [4,6,5,7].\n- Swap 6 and 5. The 3rd level becomes [4,5,6,7].\nWe used 3 operations so return 3.\nIt can be proven that 3 is the minimum number of operations needed.\n\n\n
Example 3:
\n![](\"https://assets.leetcode.com/uploads/2022/09/18/image-20220918174052-4.png\")
\n\nInput: root = [1,2,3,4,5,6]\nOutput: 0\nExplanation: Each level is already sorted in increasing order so return 0.\n\n\n
\n
Constraints:
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