Merge pull request #1381 from AlgorithmWithGod/Seol-JY

[20251111] BOJ / G4 / 좋다 / 설진영

Author: ShinHeeEul

Seol-JY/202511/11 BOJ G4 좋다.md

@@ -0,0 +1,58 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        
+        int n = Integer.parseInt(br.readLine());
+        long[] arr = new long[n];
+        
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < n; i++) {
+            arr[i] = Long.parseLong(st.nextToken());
+        }
+        
+        Arrays.sort(arr);
+        
+        int count = 0;
+        for (int i = 0; i < n; i++) {
+            if (isGood(arr, n, i)) {
+                count++;
+            }
+        }
+        
+        System.out.println(count);
+    }
+    
+    static boolean isGood(long[] arr, int n, int target) {
+        int left = 0;
+        int right = n - 1;
+        long targetValue = arr[target];
+        
+        while (left < right) {
+            if (left == target) {
+                left++;
+                continue;
+            }
+            if (right == target) {
+                right--;
+                continue;
+            }
+            
+            long sum = arr[left] + arr[right];
+            
+            if (sum == targetValue) {
+                return true;
+            } else if (sum < targetValue) {
+                left++;
+            } else {
+                right--;
+            }
+        }
+        
+        return false;
+    }
+}
+```