Merge pull request #185 from AlgorithmWithGod/khj20006

[20250226] BOJ / P1 / Communism / 권혁준

Author: ShinHeeEul

khj20006/202502/26 BOJ P1 Communism.md

@@ -0,0 +1,61 @@
+```cpp
+
+#include <iostream>
+#include <algorithm>
+using namespace std;
+using ll = long long;
+
+int N;
+ll A[30]{}, D;
+
+ll R[14348907][3]{};
+int S[2]{};
+
+void half(int k, int s, int e) {
+	for (int i = s; i < e; i++) {
+		ll a = A[i];
+		int T = S[k];
+		int id = 0, id1 = 0, id2 = 0, id3 = 0;
+		while (id1 < T) {
+			ll r1 = R[id1][k] - a, r2 = R[id2][k], r3 = R[id3][k] + a, mn = min({ r1,r2,r3 });
+			R[id++][2] = mn;
+			if (mn == r1) id1++;
+			else if (mn == r2) id2++;
+			else id3++;
+		}
+		while (id2 < T) {
+			ll r2 = R[id2][k], r3 = R[id3][k] + a, mn = min(r2, r3);
+			R[id++][2] = mn;
+			if (mn == r2) id2++;
+			else id3++;
+		}
+		S[k] *= 3;
+		while (id3 < T) R[id++][2] = R[id3++][k] + a;
+		for (int j = 0; j < id; j++) R[j][k] = R[j][2];
+	}
+}
+
+int main() {
+	cin.tie(0)->sync_with_stdio(0);
+
+	cin >> N;
+	for (int i = 0; i < N; i++) cin >> A[i];
+	cin >> D;
+
+	S[0] = S[1] = 1;
+	half(0, 0, N >> 1);
+	half(1, N >> 1, N);
+
+	ll ans = 0;
+	int s = S[1] - 1, e = S[1] - 1;
+	for (int i = 0; i < S[0]; i++) {
+		ll a = R[i][0];
+		while (s >= 0 && R[s][1] >= -D - a) s--;
+		while (e >= 0 && R[e][1] > D - a) e--;
+		ans += e - s;
+	}
+	cout << ans;
+
+}
+
+```