Second Minimum Node In a Binary Tree
给一个很特殊的二叉树, 返回第二小的值. 直接都放到list里, 然后找到值
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/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public int findSecondMinimumValue(TreeNode root) { List<Integer> list = new ArrayList<>(); bfs(root, list); Collections.sort(list); int first = -1; int second = -1; for(Integer i : list) { if(first == -1){ first = i; } else if(i != first) { second = i; break; } } return second; } private void bfs(TreeNode root, List<Integer> list) { if(root == null) return; list.add(root.val); bfs(root.left, list); bfs(root.right, list); } } |