diff --git a/problems/0530.二叉搜索树的最小绝对差.md b/problems/0530.二叉搜索树的最小绝对差.md index 77699c9f..d7db85ae 100644 --- a/problems/0530.二叉搜索树的最小绝对差.md +++ b/problems/0530.二叉搜索树的最小绝对差.md @@ -431,7 +431,84 @@ function getMinimumDifference(root: TreeNode | null): number { }; ``` +## Scala +构建二叉树的有序数组: + +```scala +object Solution { + import scala.collection.mutable + def getMinimumDifference(root: TreeNode): Int = { + val arr = mutable.ArrayBuffer[Int]() + def traversal(node: TreeNode): Unit = { + if (node == null) return + traversal(node.left) + arr.append(node.value) + traversal(node.right) + } + traversal(root) + // 在有序数组上求最小差值 + var result = Int.MaxValue + for (i <- 1 until arr.size) { + result = math.min(result, arr(i) - arr(i - 1)) + } + result // 返回最小差值 + } +} +``` + +递归记录前一个节点: + +```scala +object Solution { + def getMinimumDifference(root: TreeNode): Int = { + var result = Int.MaxValue // 初始化为最大值 + var pre: TreeNode = null // 记录前一个节点 + + def traversal(cur: TreeNode): Unit = { + if (cur == null) return + traversal(cur.left) + if (pre != null) { + // 对比result与节点之间的差值 + result = math.min(result, cur.value - pre.value) + } + pre = cur + traversal(cur.right) + } + + traversal(root) + result // return关键字可以省略 + } +} +``` + +迭代解决: + +```scala +object Solution { + import scala.collection.mutable + def getMinimumDifference(root: TreeNode): Int = { + var result = Int.MaxValue // 初始化为最大值 + var pre: TreeNode = null // 记录前一个节点 + var cur = root + var stack = mutable.Stack[TreeNode]() + while (cur != null || !stack.isEmpty) { + if (cur != null) { + stack.push(cur) + cur = cur.left + } else { + cur = stack.pop() + if (pre != null) { + result = math.min(result, cur.value - pre.value) + } + pre = cur + cur = cur.right + } + } + result // return关键字可以省略 + } +} +``` -----------------------