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Original file line number Diff line number Diff line change
Expand Up @@ -305,3 +305,51 @@ private fun isSameTree(root: TreeNode?, subRoot: TreeNode?): Boolean {

return isSameTree(root?.left, subRoot?.left) && isSameTree(root?.right, subRoot?.right)
}


/**
* 655. Print Binary Tree
*/

fun printTree(root: TreeNode?): List<List<String>> {
root ?: return listOf()

val rows = height(root)
val col = (1 shl rows) - 1
val res = MutableList(rows) { _ ->
MutableList(col) { "" }
}
val rootPos = (col - 1) / 2
val queue = LinkedList<Triple<TreeNode, Int, Int>>().apply {
val triple = Triple(root, 0, rootPos)
offer(triple)
}

while (queue.isNotEmpty()) {
val size = queue.size

for (i in 0 until size) {
val (node, level, col) = queue.poll()
val offset = 1 shl (rows - level - 2)

res[level][col] = node.`val`.toString()

node.left?.let {
val triple = Triple(it, level + 1, col - offset)
queue.offer(triple)
}

node.right?.let {
val triple = Triple(it, level + 1, col + offset)
queue.offer(triple)
}
}
}

return res
}

private fun height(root: TreeNode?): Int = when {
root == null -> 0
else -> 1 + maxOf(height(root.left), height(root.right))
}