[20251106] PGM / LV2 / 전화번호 목록 / 김민진

zinnnn37/202511/6 PGM LV2 전화번호 목록.md

@@ -0,0 +1,63 @@
+```java
+class PGM_LV2_전화번호_목록 {
+
+    private static Trie trie;
+    private static boolean answer;
+
+    private static class TrieNode {
+        TrieNode[] children;
+        boolean isEnd;
+
+        TrieNode() {
+            children = new TrieNode[10];
+            isEnd = false;
+        }
+    }
+
+    private static class Trie {
+        TrieNode root;
+
+        Trie() {
+            root = new TrieNode();
+        }
+
+        public static boolean insert(String number) {
+            TrieNode cur = trie.root;
+
+            int len = number.length();
+            for (int i = 0; i < len; i++) {
+                int idx = number.charAt(i) - '0';
+
+                if (cur.children[idx] == null) {
+                    cur.children[idx] = new TrieNode();
+                }
+
+                cur = cur.children[idx];
+
+                if (cur.isEnd) {
+                    return false;
+                }
+            }
+
+            for (int i = 0; i < 10; i++) {
+                if (cur.children[i] != null) {
+                    return false;
+                }
+            }
+            cur.isEnd = true;
+            return true;
+        }
+    }
+
+    public boolean solution(String[] phone_book) {
+        trie = new Trie();
+
+        for (String number : phone_book) {
+            if (!trie.insert(number)) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
+```