[20250608] BOJ / P2 / mex / 권혁준

khj20006/202506/08 BOJ P2 mex.md

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+```java
+import java.util.*;
+import java.io.*;
+
+class IOController {
+    BufferedReader br;
+    BufferedWriter bw;
+    StringTokenizer st;
+
+    public IOController(){
+        br = new BufferedReader(new InputStreamReader(System.in));
+        bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        st = new StringTokenizer("");
+    }
+
+    void nextLine() throws Exception {
+        st = new StringTokenizer(br.readLine());
+    }
+
+    String nextToken() throws Exception {
+        while(!st.hasMoreTokens()) nextLine();
+        return st.nextToken();
+    }
+
+    int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+    long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+    double nextDouble() throws Exception { return Double.parseDouble(nextToken()); }
+
+    void close() throws Exception {
+        bw.flush();
+        bw.close();
+    }
+
+    void write(String content) throws Exception {
+        bw.write(content);
+    }
+
+}
+
+class Node {
+    Node left, right;
+    Node() {
+        left = null;
+        right = null;
+    }
+}
+
+class Trie {
+    Node root;
+    Trie(){
+        root = new Node();
+    }
+
+    // 정수 x 삽입
+    void insert(int x) {
+        int k = 1<<18;
+        Node now = root;
+        while(k > 0) {
+            int bit = x & k;
+            if(bit == 0) {
+                if(now.left == null) now.left = new Node();
+                now = now.left;
+            }
+            else {
+                if(now.right == null) now.right = new Node();
+                now = now.right;
+            }
+            k >>= 1;
+        }
+    }
+
+    // x와 XOR 했을 때의 최솟값 찾기
+    int find(int x) {
+        int k = 1<<18, res = 0;
+        Node now = root;
+        while(k > 0) {
+            int bit = x & k;
+            if(bit == 0) {
+                if(now.left == null){
+                    res |= k;
+                    now = now.right;
+                }
+                else{
+                    now = now.left;
+                }
+            }
+            else {
+                if(now.right == null) {
+                    res |= k;
+                    now = now.left;
+                }
+                else{
+                    now = now.right;
+                }
+            }
+            k >>= 1;
+        }
+        return res;
+    }
+}
+
+public class Main {
+
+    static IOController io;
+
+    //
+
+    static int N, M;
+    static boolean[] exist;
+    static Trie trie;
+
+    public static void main(String[] args) throws Exception {
+
+        io = new IOController();
+
+        init();
+        solve();
+
+        io.close();
+
+    }
+
+    public static void init() throws Exception {
+
+        N = io.nextInt();
+        M = io.nextInt();
+        exist = new boolean[524288];
+        for(int i=1;i<=N;i++) exist[io.nextInt()] = true;
+
+        trie = new Trie();
+        for(int i=0;i<524288;i++) if(!exist[i]) trie.insert(i);
+
+    }
+
+    static void solve() throws Exception {
+
+        int X = 0;
+        for(int i=0;i<M;i++) {
+            X ^= io.nextInt();
+            io.write(trie.find(X) + "\n");
+        }
+
+    }
+
+
+}
+```