Submission #1165081

#TimeUsernameProblemLanguageResultExecution timeMemory
1165081KickingKunBoat (APIO16_boat)C++20
36 / 100
2096 ms5388 KiB
// PHK #include <bits/stdc++.h> using namespace std; #define ll long long #define ull unsigned long long #define ld long double #define bigint __int128 #define emb emplace_back #define pb push_back #define pii pair <int, int> #define fi first #define se second #define all(v) v.begin(), v.end() #define Task "" #define MASK(k) (1ull << k) #define bitcnt(k) __builtin_popcount(k) #define testBit(n, k) ((n >> k) & 1) #define flipBit(n, k) (n ^ (1ll << k)) #define offBit(n, k) (n & ~MASK(k)) #define onBit(n, k) (n | (1ll << k)) template <class T> bool minimize(T &a, T b) {if (a > b) {a = b; return true;} return false;} template <class T> bool maximize(T &a, T b) {if (a < b) {a = b; return true;} return false;} const int N = 5e2 + 5, lim = 60, mod = 1e9 + 7; const ll INF = 1e18; int n, l[N], r[N], C[N << 1][N], combi[N][N]; int dp[N][N << 1]; ll powMod(ll a, ll b) { if (b == 0) return 1; ll tmp = powMod(a, b >> 1); return (b & 1) ? (tmp * tmp % mod * a % mod) : (tmp * tmp % mod); } // dp[i][j]: ways first i schools such that the number of boats sent <= pts[j] void add(int &a, int b) { if ((a += b) >= mod) a -= mod; } int main() { ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); if (fopen(Task".inp", "r")) { freopen(Task".inp", "r", stdin); freopen(Task".out", "w", stdout); } cin >> n; vector <int> points; for (int i = 1; i <= n; i++) { cin >> l[i] >> r[i]; --l[i]; points.emplace_back(l[i]); points.emplace_back(r[i]); } sort (all(points)); points.resize(unique(all(points)) - points.begin()); // C(n, k) = C(n, k-1) * (n-k+1) / k for (int i = 1; i < points.size(); i++) { C[i][1] = points[i] - points[i - 1]; for (int j = 2; j <= n; j++) C[i][j] = 1ll * C[i][j - 1] * (points[i] - points[i - 1] - j + 1) % mod * powMod(j, mod - 2) % mod; } combi[0][0] = 1; for (int i = 1; i <= n; i++) { combi[0][i] = 1; for (int j = 1; j <= i; j++) combi[j][i] = (combi[j - 1][i - 1] + combi[j][i - 1]) % mod; } for (int j = 0; j < points.size(); j++) dp[0][j] = 1; for (int i = 1; i <= n; i++) { dp[i][0] = 1; for (int j = 1; j < points.size(); j++) { dp[i][j] = dp[i][j - 1]; for (int k = i, cnt = 0; k > 0; k--) { if (l[k] < points[j] && points[j] <= r[k]) { ++cnt; int S = 0; for (int t = 0; t < cnt; t++) add(S, 1ll * combi[t][cnt - 1] * C[j][t + 1] % mod); add(dp[i][j], 1ll * dp[k - 1][j - 1] * S % mod); } } } } cout << (dp[n][points.size() - 1] - 1 + mod) % mod; }

Compilation message (stderr)

boat.cpp: In function 'int main()':
boat.cpp:49:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |                 freopen(Task".inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
boat.cpp:50:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |                 freopen(Task".out", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
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