diff --git "a/Seol-JY/202511/11 BOJ G4 \354\242\213\353\213\244.md\342\200\216" "b/Seol-JY/202511/11 BOJ G4 \354\242\213\353\213\244.md\342\200\216" new file mode 100644 index 00000000..2762de18 --- /dev/null +++ "b/Seol-JY/202511/11 BOJ G4 \354\242\213\353\213\244.md\342\200\216" @@ -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; + } +} +```