기록하는 공간

Stack을 이용한 풀이 import java.util.*; class Solution { private String getStackToString(String s) { Stack stack = new Stack(); for (char c : s.toCharArray()) { if (!stack.empty() && c == '#') { stack.pop(); } else if (c != '#') { stack.push(c); } } return stack.toString(); } public boolean backspaceCompare(String S, String T) { String s = getStackToString(S); String t = getStackToString(T); return s...

/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public TreeNode mergeTrees(TreeNode t1, TreeNode t2) { return merge(t1, t2); } public TreeNode merge(TreeNode t1, TreeNode t2) { if (t1 == null) return t2; if (t2 == null) return t1; t1.val += t2.val t1.left = merge(t1.left, t2.le..