Bình luận

• 
  

  0

  

  nhankiettvt  đã bình luận lúc 22, Tháng 7, 2026, 6:29

  code full ac cho ae

  #include <algorithm>
  #include <bitset>
  #include <climits>
  #include <cmath>
  #include <cstdio>
  #include <iomanip>
  #include <iostream>
  #include <map>
  #include <queue>
  #include <set>
  #include <stack>
  #include <string>
  #include <unordered_map>
  #include <utility>
  #include <vector>
  
  using namespace std;
  
  #define pii pair&lt;int, int>
  #define pll pair&lt;ll, ll>
  #define vi vector<int>
  #define vll vector<ll>
  #define fi first
  #define se second
  #define pb push_back
  #define all(x) (x).begin(), (x).end()
  #define ll long long
  #define ull unsigned long long
  
  #define FOR(i, a, b) for (int i = (a); i <= (b); ++i)
  #define FORD(i, a, b) for (int i = (a); i >= (b); --i)
  #define REP(i, n) for (int i = 0; i < (n); ++i)
  
  void fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
  }
  void solve() {}
  vector<int> o;
  bool is_nguyen_to(int n) {
    if (n < 2)
      return 0;
    for (int i = 2; i <= sqrt(n); i++) {
      if (n % i == 0)
        return 0;
    }
    return 1;
  }
  void b() {
    for (int i = 2; i <= 100000; i++) {
      if (is_nguyen_to(i)) {
        o.push_back(i);
      }
    }
  }
  int main() {
    fast_io();
    int k;
    cin >> k;
    ull dem = 0;
    b();
    ull n = o.size();
    if (k <= 100) {
      for (int i = 0; i <= k; i++) {
        for (int j = i; j <= k; j++) {
          for (int z = j; z <= k; z++) {
            if (i + j + z == k && is_nguyen_to(i) && is_nguyen_to(j) &&
                is_nguyen_to(z)) {
              dem++;
            }
          }
        }
      }
    } else {
      for (int i = 0; i < n; i++) {
        for (int j = i; j < n; j++) {
          if (k - (o[i] + o[j]) > 0 && is_nguyen_to(k - (o[i] + o[j])) &&
              o[i] <= o[j] && o[j] <= k - (o[i] + o[j])) {
            dem++;
          }
        }
      }
    }
    cout << dem;
    return 0;
  }
  

• 
  

  -1

  

  nhatminecraftthanhgu  đã bình luận lúc 24, Tháng 4, 2026, 2:43

  code cho ae:

  include <bits/stdc++.h>

  using namespace std;

  const int N = 100000; bool isPrime[N + 1];

  void sieve() { fill(isPrime, isPrime + N + 1, true); isPrime[0] = isPrime[1] = false;

  for (int i = 2; i * i <= N; i++) {
      if (isPrime[i]) {
          for (int j = i * i; j <= N; j += i)
              isPrime[j] = false;
      }
  }
  

  }

  int main() { ios::syncwithstdio(false); cin.tie(nullptr);

  int k;
  cin >> k;
  
  sieve();
  
  int ans = 0;
  
  for (int x = 2; x <= k; x++) {
      if (!isPrime[x]) continue;
  
      for (int y = x; y <= k; y++) {
          if (!isPrime[y]) continue;
  
          int z = k - x - y;
          if (z < y) break;
          if (z > N) continue;
  
          if (isPrime[z]) ans++;
      }
  }
  
  cout << ans;
  return 0;
  

  }