[20251111] BOJ / G4 / 좋다 / 한종욱

Author: Ukj0ng

Ukj0ng/202511/11 BOJ G4 좋다.md

@@ -0,0 +1,58 @@
+```
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static int[] arr;
+    private static int N, answer;
+    public static void main(String[] args) throws IOException {
+        init();
+
+        if (N == 1) bw.write(1 + "\n");
+        else answer = twoPointer();
+
+        bw.write(answer + "\n");
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        N = Integer.parseInt(br.readLine());
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        arr = new int[N];
+
+        for (int i = 0; i < N; i++) {
+            arr[i] = Integer.parseInt(st.nextToken());
+        }
+
+        Arrays.sort(arr);
+    }
+
+    private static int twoPointer() {
+        int result = 0;
+
+        for (int i = 0; i < N; i++) {
+            int left = 0;
+            int right = N-1;
+            while (left < right) {
+                if (left == i) left++;
+                else if (right == i) right--;
+                else if (arr[left]+arr[right] == arr[i]) {
+                    result++;
+                    break;
+                } else if (arr[left]+arr[right] > arr[i]) {
+                    right--;
+                } else {
+                    left++;
+                }
+            }
+        }
+
+        return result;
+    }
+}
+```