From cd98166da5c0cc84fd1cd8bbf1b17568760d856c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EC=9E=84=EC=8A=B9=ED=98=B8?=
 <132066506+YIM2UL2ET@users.noreply.github.com>
Date: Fri, 19 Apr 2024 17:23:39 +0900
Subject: [PATCH] =?UTF-8?q?18=EC=B0=A8=EC=8B=9C=20=EC=97=85=EB=A1=9C?=
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---
 YIM2UL2ET/README.md                           |  2 +-
 ...18\354\260\250\354\213\234 - BOJ 5639.cpp" | 34 +++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 "YIM2UL2ET/\355\212\270\353\246\254/18\354\260\250\354\213\234 - BOJ 5639.cpp"

diff --git a/YIM2UL2ET/README.md b/YIM2UL2ET/README.md
index d868578..57c0ce8 100644
--- a/YIM2UL2ET/README.md
+++ b/YIM2UL2ET/README.md
@@ -19,5 +19,5 @@
 | 15차시 | 2024.04.09 |  구현  | [BOJ 14719](https://www.acmicpc.net/problem/14719)  | [BOJ 14719 풀이](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/48) |
 | 16차시 | 2024.04.11 |  애드 혹  | [BOJ 15927](https://www.acmicpc.net/problem/15927)  | [BOJ 15927 풀이](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/51) |
 | 17차시 | 2024.04.15 |  DP  | [BOJ 11726](https://www.acmicpc.net/problem/11726)  | [BOJ 11726 풀이](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/53) |
-
+| 18차시 | 2024.04.15 |  트리  | [BOJ 5639](https://www.acmicpc.net/problem/5639)  | [BOJ 5639 풀이](https://github.com/AlgoLeadMe/AlgoLeadMe-7/pull/53) |
 ---
\ No newline at end of file
diff --git "a/YIM2UL2ET/\355\212\270\353\246\254/18\354\260\250\354\213\234 - BOJ 5639.cpp" "b/YIM2UL2ET/\355\212\270\353\246\254/18\354\260\250\354\213\234 - BOJ 5639.cpp"
new file mode 100644
index 0000000..ed5a18c
--- /dev/null
+++ "b/YIM2UL2ET/\355\212\270\353\246\254/18\354\260\250\354\213\234 - BOJ 5639.cpp"	
@@ -0,0 +1,34 @@
+#include <iostream>
+using namespace std;
+
+struct node {
+    int value = -1;
+    node* right = NULL;
+    node* left = NULL;
+};
+
+void input(node &nd, int n) {
+    if (nd.value == -1) nd.value = n;
+    else if (nd.value > n) {
+        if (nd.left == NULL) nd.left = new node;
+        input(*nd.left, n); 
+    }
+    else {
+        if (nd.right == NULL) nd.right = new node;
+        input(*nd.right, n); 
+    }
+}
+
+void output(node &nd) {
+    if (nd.left != NULL) output(*nd.left);
+    if (nd.right != NULL) output(*nd.right);
+    cout << nd.value << '\n';
+}
+
+int main(void) {
+    int n;
+    node root;
+    while (cin >> n) input(root, n);
+    output(root);
+    return 0;
+}
\ No newline at end of file