[20251022] BOJ / G3 / 좋은 수 / 권혁준

Author: oncsr

khj20006/202510/22 BOJ G3 좋은 수.md

@@ -0,0 +1,25 @@
+```cpp
+#include <bits/stdc++.h>
+using namespace std;
+
+int N, a[5000]{};
+bitset<400001> v;
+
+int main() {
+	cin.tie(0)->sync_with_stdio(0);
+
+	cin >> N;
+	int ans = 0;
+	for (int i = 0; i < N; i++) {
+		cin >> a[i];
+		int res = 0;
+		for (int j = 0; j < i; j++) {
+			if (v[a[i] - a[j] + 200000]) res = 1;
+		}
+		for (int j = 0; j <= i; j++) v[a[i] + a[j] + 200000] = 1;
+		ans += res;
+	}
+	cout << ans;
+
+}
+```