Maximum Difference Between Node and Ancestor

1026. Maximum Difference Between Node and Ancestor/Maximum Difference Between Node and Ancestor.go

@@ -0,0 +1,61 @@
+package problem1026
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func abs(num int) int {
+	if num < 0 {
+		return -num
+	}
+	return num
+}
+
+func getMax(nums ...int) int {
+	max := nums[0]
+	for _, num := range nums {
+		if max < num {
+			max = num
+		}
+	}
+	return max
+
+}
+func getMin(nums ...int) int {
+	min := nums[0]
+	for _, num := range nums {
+		if min > num {
+			min = num
+		}
+	}
+	return min
+
+}
+func dFS(root *TreeNode) (min, max, diff int) {
+	if root == nil {
+		return 100001, -1, 0
+	}
+	lMin, lMax, lDiff := dFS(root.Left)
+	rMin, rMax, rDiff := dFS(root.Right)
+	min = getMin(lMin, rMin)
+	max = getMax(lMax, rMax)
+	diff = getMax(lDiff, rDiff)
+	if min < 100001 {
+		diff = getMax(diff, abs(root.Val-min))
+	}
+	if max > -1 {
+		diff = getMax(diff, abs(root.Val-max))
+	}
+
+	min = getMin(min, root.Val)
+	max = getMax(lMax, rMax, root.Val)
+	return
+
+}
+func maxAncestorDiff(root *TreeNode) int {
+	_, _, res := dFS(root)
+	return res
+
+}