[20251207] BOJ / G5 / 환승 / 두 수의 합

Author: Ukj0ng

Ukj0ng/202512/07 BOJ G5 두 수의 합.md

@@ -0,0 +1,66 @@
+```
+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, K;
+
+    public static void main(String[] args) throws IOException {
+        int T = Integer.parseInt(br.readLine());
+
+        while (T-->0) {
+            init();
+            int answer = binarySearch();
+            bw.write(answer + "\n");
+        }
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        K = Integer.parseInt(st.nextToken());
+
+        arr = new int[N];
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) {
+            arr[i] = Integer.parseInt(st.nextToken());
+        }
+
+        Arrays.sort(arr);
+    }
+
+    private static int binarySearch() {
+        int left = 0;
+        int right = N-1;
+
+        int minGap = (int)1e8 + 1;
+        int count = 0;
+
+        while (left < right) {
+            int sum = arr[left] + arr[right];
+            int gap = Math.abs(sum - K);
+
+            if (gap < minGap) {
+                minGap = gap;
+                count = 1;
+            } else if (gap == minGap) {
+                count++;
+            }
+
+            if (sum < K) {
+                left++;
+            } else {
+                right--;
+            }
+        }
+
+        return count;
+    }
+}
+```