.\979.distribute-coins-in-binary-tree ok

侯利朋 · 侯利朋 · commit f67efa03dfc9 · 2019-08-30T15:15:58.000+08:00
diff --git a/979.distribute-coins-in-binary-tree.go b/979.distribute-coins-in-binary-tree.go
@@ -0,0 +1,38 @@
+/*
+ * @lc app=leetcode id=979 lang=golang
+ *
+ * [979] Distribute Coins in Binary Tree
+ */
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+//  (0 ms)
+func distributeCoins(root *TreeNode) int {
+	rtn := 0
+	moves(root, &rtn)
+	return rtn
+}
+
+// root树平衡需要从外面获取的节点数，可能正，可能负
+func moves(root *TreeNode, ans *int) int {
+	if root == nil {
+		return 0
+	}
+
+	l := moves(root.Left, ans)
+	r := moves(root.Right, ans)
+	*ans += abs(l) + abs(r) // 移动的数目和root.Val 没有关系
+	return root.Val - 1 + l + r
+}
+
+func abs(a int) int {
+	if a < 0 {
+		return -a
+	}
+	return a
+}
