제출 #222702

#제출 시각아이디문제언어결과실행 시간메모리
222702Minnakhmetov캥거루 (CEOI16_kangaroo)C++14
0 / 100
5 ms512 KiB
#include <bits/stdc++.h> using namespace std; #define ll long long #define all(aaa) aaa.begin(), aaa.end() const int N = 205, MOD = 1e9 + 7; int dp[N][N][N][2], pref[N][N][N][2]; void add(int &a, int b) { a += b; if (a >= MOD) a -= MOD; } int main() { ios_base::sync_with_stdio(false); cin.tie(NULL); int n, cs, cf; cin >> n >> cs >> cf; if (cf > cs) swap(cf, cs); dp[2][2][1][1]++; dp[2][1][2][0]++; pref[2][2][1][1]++; pref[2][2][2][1]++; pref[2][1][2][0]++; for (int i = 3; i <= n; i++) { for (int k = 1; k <= i; k++) { for (int j = k + 1; j <= i; j++) { add(dp[i][k][j][0], pref[i - 1][k][j - 1][1]); add(dp[i][k][j][1], pref[i - 1][k][i - 1][0]); add(dp[i][k][j][1], MOD - pref[i - 1][k][j - 1][0]); add(dp[i][k][j][1], pref[i - 1][k][k][0]); add(dp[i][k][j][1], MOD - pref[i - 1][i - 1 - k][i - 1 - k][1]); } for (int j = 1; j < k; j++) { dp[i][k][j][0] = dp[i][j][k][(i & 1) ^ 1]; dp[i][k][j][1] = dp[i][j][k][(i & 1)]; } for (int j = 1; j <= i; j++) { pref[i][k][j][0] = pref[i][k][j - 1][0]; pref[i][k][j][1] = pref[i][k][j - 1][1]; add(pref[i][k][j][0], dp[i][k][j][0]); add(pref[i][k][j][1], dp[i][k][j][1]); } } } int ans = (dp[n][cf][cs][0] + dp[n][cf][cs][1]) % MOD; cout << ans; // for (int i = 1; i <= n; i++) { // for (int j = 1; j <= n; j++) { // cout << dp[n][i][j][0] << " "; // } // cout << "\n"; // } return 0; }
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