diff --git a/problems/0111.二叉树的最小深度.md b/problems/0111.二叉树的最小深度.md index 6c6b4632..21cf36df 100644 --- a/problems/0111.二叉树的最小深度.md +++ b/problems/0111.二叉树的最小深度.md @@ -194,6 +194,61 @@ public: Java: +```Java +class Solution { + /** + * 递归法,相比求MaxDepth要复杂点 + * 因为最小深度是从根节点到最近**叶子节点**的最短路径上的节点数量 + */ + public int minDepth(TreeNode root) { + if (root == null) { + return 0; + } + int leftDepth = minDepth(root.left); + int rightDepth = minDepth(root.right); + if (root.left == null) { + return rightDepth + 1; + } + if (root.right == null) { + return leftDepth + 1; + } + // 左右结点都不为null + return Math.min(leftDepth, rightDepth) + 1; + } +} + +class Solution { + /** + * 迭代法,层序遍历 + */ + public int minDepth(TreeNode root) { + if (root == null) { + return 0; + } + Deque deque = new LinkedList<>(); + deque.offer(root); + int depth = 0; + while (!deque.isEmpty()) { + int size = deque.size(); + depth++; + for (int i = 0; i < size; i++) { + TreeNode poll = deque.poll(); + if (poll.left == null && poll.right == null) { + // 是叶子结点,直接返回depth,因为从上往下遍历,所以该值就是最小值 + return depth; + } + if (poll.left != null) { + deque.offer(poll.left); + } + if (poll.right != null) { + deque.offer(poll.right); + } + } + } + return depth; + } +} +``` Python: @@ -250,4 +305,4 @@ Go: * 作者微信:[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) * B站视频:[代码随想录](https://space.bilibili.com/525438321) * 知识星球:[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ) -
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