1302. Deepest Leaves Sum #
题目 #
Given a binary tree, return the sum of values of its deepest leaves.
Example 1:
Input: root = [1,2,3,4,5,null,6,7,null,null,null,null,8]
Output: 15
Constraints:
- The number of nodes in the tree is between
1and10^4. - The value of nodes is between
1and100.
题目大意 #
给你一棵二叉树，请你返回层数最深的叶子节点的和。
提示：
- 树中节点数目在 1 到 10^4 之间。
- 每个节点的值在 1 到 100 之间。
解题思路 #
- 给你一棵二叉树，请你返回层数最深的叶子节点的和。
- 这一题不难，DFS 遍历把最底层的叶子节点和都加起来即可。
代码 #
func deepestLeavesSum(root *TreeNode) int {
maxLevel, sum := 0, 0
dfsDeepestLeavesSum(root, 0, &maxLevel, &sum)
return sum
}
func dfsDeepestLeavesSum(root *TreeNode, level int, maxLevel, sum *int) {
if root == nil {
return
}
if level > *maxLevel {
*maxLevel, *sum = level, root.Val
} else if level == *maxLevel {
*sum += root.Val
}
dfsDeepestLeavesSum(root.Left, level+1, maxLevel, sum)
dfsDeepestLeavesSum(root.Right, level+1, maxLevel, sum)
}