結果
問題 | No.1657 Sum is Prime (Easy Version) |
ユーザー |
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提出日時 | 2021-08-27 22:31:21 |
言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 2 ms / 2,000 ms |
コード長 | 2,109 bytes |
コンパイル時間 | 1,997 ms |
コンパイル使用メモリ | 207,932 KB |
最終ジャッジ日時 | 2025-01-24 03:22:05 |
ジャッジサーバーID (参考情報) |
judge1 / judge1 |
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ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 21 |
ソースコード
#include <bits/stdc++.h> using namespace std; //Counting Primes //https://judge.yosupo.jp/submission/53928 より using i64 = long long; int isqrt(i64 n) { return sqrtl(n); } __attribute__((target("avx2"), optimize("O3", "unroll-loops"))) i64 prime_pi(const i64 N) { if (N <= 1) return 0; if (N == 2) return 1; const int v = isqrt(N); int s = (v + 1) / 2; vector<int> smalls(s); for (int i = 1; i < s; ++i) smalls[i] = i; vector<int> roughs(s); for (int i = 0; i < s; ++i) roughs[i] = 2 * i + 1; vector<i64> larges(s); for (int i = 0; i < s; ++i) larges[i] = (N / (2 * i + 1) - 1) / 2; vector<bool> skip(v + 1); const auto divide = [] (i64 n, i64 d) -> int { return double(n) / d; }; const auto half = [] (int n) -> int { return (n - 1) >> 1; }; int pc = 0; for (int p = 3; p <= v; p += 2) if (!skip[p]) { int q = p * p; if (i64(q) * q > N) break; skip[p] = true; for (int i = q; i <= v; i += 2 * p) skip[i] = true; int ns = 0; for (int k = 0; k < s; ++k) { int i = roughs[k]; if (skip[i]) continue; i64 d = i64(i) * p; larges[ns] = larges[k] - (d <= v ? larges[smalls[d >> 1] - pc] : smalls[half(divide(N, d))]) + pc; roughs[ns++] = i; } s = ns; for (int i = half(v), j = ((v / p) - 1) | 1; j >= p; j -= 2) { int c = smalls[j >> 1] - pc; for (int e = (j * p) >> 1; i >= e; --i) smalls[i] -= c; } ++pc; } larges[0] += i64(s + 2 * (pc - 1)) * (s - 1) / 2; for (int k = 1; k < s; ++k) larges[0] -= larges[k]; for (int l = 1; l < s; ++l) { int q = roughs[l]; i64 M = N / q; int e = smalls[half(M / q)] - pc; if (e < l + 1) break; i64 t = 0; for (int k = l + 1; k <= e; ++k) t += smalls[half(divide(M, roughs[k]))]; larges[0] += t - i64(e - l) * (pc + l - 1); } return larges[0] + 1; } //ここまで signed main(){ long long L, R; cin >> L >> R; long long ans = prime_pi(R) - prime_pi(L - 1); if(L < R){ ans += prime_pi(2 * R - 1) - prime_pi(2 * L - 1); if(2 * L - 1 < 2) ans--; } cout << ans << endl; return 0; }