diff --git "a/Ukj0ng/202511/11 BOJ G4 \354\242\213\353\213\244.md" "b/Ukj0ng/202511/11 BOJ G4 \354\242\213\353\213\244.md" new file mode 100644 index 00000000..4e51f181 --- /dev/null +++ "b/Ukj0ng/202511/11 BOJ G4 \354\242\213\353\213\244.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; + } +} +```