Submission #1085999

#TimeUsernameProblemLanguageResultExecution timeMemory
1085999quanlt206Boat (APIO16_boat)C++17
0 / 100
2 ms348 KiB
#include<bits/stdc++.h> #define X first #define Y second #define all(x) begin(x), end(x) #define FOR(i, a, b) for(int i = (a); i <= (b); i++) #define FORD(i, b, a) for(int i = (b); i >= (a); i--) #define REP(i, a, b) for (int i = (a); i < (b); i++) #define mxx max_element #define mnn min_element #define SQR(x) (1LL * (x) * (x)) #define MASK(i) (1LL << (i)) #define Point Vector #define left Left #define right Right #define div Div using namespace std; typedef long long ll; typedef unsigned long long ull; typedef double db; typedef long double ld; typedef pair<db, db> pdb; typedef pair<ld, ld> pld; typedef pair<int, int> pii; typedef pair<int, pii> piii; typedef pair<ll, ll> pll; typedef pair<ll, pll> plll; typedef pair<ll, int> pli; typedef pair<ll, pii> plii; template<class A, class B> bool maximize(A& x, B y) { if (x < y) return x = y, true; else return false; } template<class A, class B> bool minimize(A& x, B y) { if (x > y) return x = y, true; else return false; } /* END OF TEMPLATE */ const int N = 2e3 + 7; const int mod = 1e9 + 7; int n, m, a[N], b[N]; vector<int> E; pii block[N]; int dp[2][2000][2000][2]; void add(int& x, int y) { if ((x+=y) >= mod) x-=mod; } int Ckn[N][N]; long long fact[N], inv_fact[N]; long long mul(long long a, long long b) { if (b == 0) return 1; ll tmp = mul(a, b / 2); tmp = tmp * tmp % mod; if (b & 1) tmp = tmp * a % mod; return tmp; } void buildCkn() { fact[0] = 1; for (int i = 1; i <= n; i++) fact[i] = fact[i - 1] * i % mod; inv_fact[n] = mul(fact[n], mod - 2); for (int i = n - 1; i > 0; i--) inv_fact[i] = inv_fact[i + 1] * (i + 1) % mod; for (int i = 1; i <= m; i++) { int sz = block[i].Y - block[i].X + 1; ll tich = 1; for (int j = sz; j > 0; j--) { tich = tich * j % mod; Ckn[i][sz - j + 1] = tich * inv_fact[sz - j + 1] % mod; // cout<<sz<<" "<<sz - j + 1<<" "<< Ckn[i][sz - j + 1]<<"\n"; if (sz - j + 1 > n) break; } } } int cnt[N]; int main() { #ifndef ONLINE_JUDGE freopen("code.inp", "r", stdin); freopen("code.out", "w", stdout); #endif // ONLINE_JUDGE ios_base::sync_with_stdio(0); cin.tie(0); cin>>n; set<int> s; for (int i = 1; i <= n; i++) { cin>>a[i]>>b[i]; s.insert(a[i]); s.insert(b[i]); } vector<int> E(s.begin(), s.end()); for (int i = 0; i < E.size(); i++) { block[++m] = {E[i], E[i]}; if (i + 1 < E.size() && E[i] + 1 <= E[i + 1] - 1) block[++m] = {E[i] + 1, E[i + 1] - 1}; } buildCkn(); for (int i = 1; i <= n; i++) { for (int j = 0; j <= m; j++) if (a[i] <= block[j].X && block[j].Y <= b[i]) cnt[j]++; } cnt[0] = n; for (int i = 0; i <= n; i++) { for (int j = 0; j <= m; j++) if (a[i] <= block[j].X && block[j].Y <= b[i]) cnt[j]--; for (int j = 0; j <= m; j++) for (int k = 0; k <= cnt[j]; k++) for (int z = 0; z <= 1; z++) { int& res = dp[i & 1][j][k][z]; res = 0; if (i == 0) { res = Ckn[j][k]; continue; } if (a[i] <= block[j].X && block[j].Y <= b[i]) add(res, dp[i & 1 ^ 1][j][k + 1][0]); if (z == 0) add(res, dp[i & 1 ^ 1][j][k][0]); if (j > 0 && k > 0) add(res, 1LL * dp[i & 1][j - 1][0][1] * Ckn[j][k] % mod); else if (j > 0 && k == 0) add(res, dp[i & 1][j - 1][0][1]); } } cout<<dp[n & 1][m][0][0]; return 0; }

Compilation message (stderr)

boat.cpp: In function 'int main()':
boat.cpp:104:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  104 |     for (int i = 0; i < E.size(); i++) {
      |                     ~~^~~~~~~~~~
boat.cpp:106:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |         if (i + 1 < E.size() && E[i] + 1 <= E[i + 1] - 1) block[++m] = {E[i] + 1, E[i + 1] - 1};
      |             ~~~~~~^~~~~~~~~~
boat.cpp:126:81: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
  126 |                     if (a[i] <= block[j].X && block[j].Y <= b[i]) add(res, dp[i & 1 ^ 1][j][k + 1][0]);
      |                                                                               ~~^~~
boat.cpp:127:47: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
  127 |                     if (z == 0) add(res, dp[i & 1 ^ 1][j][k][0]);
      |                                             ~~^~~
boat.cpp:91:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   91 |     freopen("code.inp", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
boat.cpp:92:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |     freopen("code.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
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