Add solution 0530、783

leetcode/0530.Minimum-Absolute-Difference-in-BST/530. Minimum Absolute Difference in BST.go

@@ -0,0 +1,51 @@
+package leetcode
+
+import (
+	"math"
+
+	"github.com/halfrost/LeetCode-Go/structures"
+)
+
+// TreeNode define
+type TreeNode = structures.TreeNode
+
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+
+func getMinimumDifference(root *TreeNode) int {
+	res, nodes := math.MaxInt16, -1
+	dfsBST(root, &res, &nodes)
+	return res
+}
+
+func dfsBST(root *TreeNode, res, pre *int) {
+	if root == nil {
+		return
+	}
+	dfsBST(root.Left, res, pre)
+	if *pre != -1 {
+		*res = min(*res, abs(root.Val-*pre))
+	}
+	*pre = root.Val
+	dfsBST(root.Right, res, pre)
+}
+
+func min(a, b int) int {
+	if a > b {
+		return b
+	}
+	return a
+}
+
+func abs(a int) int {
+	if a > 0 {
+		return a
+	}
+	return -a
+}