Submission #556589

#TimeUsernameProblemLanguageResultExecution timeMemory
556589InternetPerson10Boat (APIO16_boat)C++17
Compilation error
0 ms0 KiB
#pragma GCC target ("avx2") #pragma GCC optimization ("O3") #pragma GCC optimization ("unroll-loops") #include <bits/stdc++.h> typedef long long ll; using namespace std; const ll MOD = 1e9 + 7; ll modpow(ll n, ll e) { if(e == 0) return 1; ll x = modpow(n, e/2); x *= x; x %= MOD; if(e%2) { x *= n; x %= MOD; } return x; } ll modinv(ll n) { return modpow(n, MOD - 2); } ll fact[5001]; ll invfact[5001]; ll binom(ll n, ll k) { // Assumes k is quite small if(k > n) return 0; if(k == n) return 1; ll ans = 1; if(n-k <= 5000) { ans = fact[n]; ans *= invfact[n-k]; ans %= MOD; } else { for(ll i = n-k+1; i <= n; i++) { ans *= i; ans %= MOD; } } ans *= invfact[k]; ans %= MOD; return ans; } void precalc() { fact[0] = 1; for(int i = 1; i <= 5000; i++) { fact[i] = (fact[i-1] * i) % MOD; } for(int i = 0; i <= 5000; i++) { invfact[i] = modinv(fact[i]); } } ll ans[501][1001], pref[501][1001]; int main() { ios::sync_with_stdio(false); cin.tie(0); precalc(); int n; cin >> n; vector<int> nums(2 * n), a(n+1), b(n+1); for(int i = 1; i <= n; i++) { cin >> a[i] >> b[i]; b[i]++; nums[2*i - 2] = a[i]; nums[2*i - 1] = b[i]; } sort(nums.begin(), nums.end()); nums.resize(unique(nums.begin(), nums.end()) - nums.begin()); for(int i = 1; i <= n; i++) { for(int j = 1; j < nums.size(); j++) { if(!(a[i] <= nums[j-1] && nums[j] <= b[i])) { continue; } ll siz = nums[j] - nums[j-1]; ans[i][j] += siz * (pref[i-1][j-1] + 1) ans[i][j] %= MOD; int g = 1; for(int k = i-1; k > 0; k--) { if(a[k] <= nums[j-1] && nums[j] <= b[k]) { g++; ll x = siz; for(int l = 2; l <= g; l++) { x *= siz-l+1; x %= MOD; x *= modinv(l); x %= MOD; ans[i][j] += ((x * binom(g-2, l-2)) % MOD) * (1 + pref[k-1][j-1]); ans[i][j] %= MOD; } } } } for(int j = 1; j < nums.size(); j++) { pref[i][j] += ans[i][j] + pref[i][j-1] + pref[i-1][j] - pref[i-1][j-1]; pref[i][j] += MOD; pref[i][j] %= MOD; } } cout << pref[n][nums.size()-1] << endl; }

Compilation message (stderr)

boat.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization ("O3")
      | 
boat.cpp:3: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    3 | #pragma GCC optimization ("unroll-loops")
      | 
boat.cpp: In function 'int main()':
boat.cpp:78:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   78 |         for(int j = 1; j < nums.size(); j++) {
      |                        ~~^~~~~~~~~~~~~
boat.cpp:83:52: error: expected ';' before 'ans'
   83 |             ans[i][j] += siz * (pref[i-1][j-1] + 1)
      |                                                    ^
      |                                                    ;
   84 |             ans[i][j] %= MOD;
      |             ~~~                                     
boat.cpp:101:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |         for(int j = 1; j < nums.size(); j++) {
      |                        ~~^~~~~~~~~~~~~