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#pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #include <iostream> #include <cstring> #include <set> #include <queue> #include <algorithm> #include <vector> #include <map> #include <cctype> #include <stack> #define freopenr freopen("in.txt", "r", stdin) #define freopenw freopen("out.txt", "w", stdout) using namespace std; typedef long long LL; typedef pair<int, int> P; const int INF = 0x3f3f3f3f; const double inf = 0x3f3f3f3f3f3f; const LL LNF = 100000000000000000; const double PI = acos(-1.0); const double eps = 1e-8; const int maxn = 1e3 + 5; const int mod = 1e9 + 7; const char *mark = "+-*"; const int dr[] = {-1, 0, 1, 0}; const int dc[] = {0, 1, 0, -1}; int n, m; inline bool is_in(int r, int c){ return r >= 0 && r < n && c >= 0 && c < m; } inline LL Max(LL a, LL b){ return a < b ? b : a; } inline LL Min(LL a, LL b){ return a > b ? b : a; } inline int Max(int a, int b){ return a < b ? b : a; } inline int Min(int a, int b){ return a > b ? b : a; } LL dp[maxn][5]; int main(){ while(cin >> n){ dp[4][0] = 7; dp[4][1] = 5; dp[4][2] = 3; dp[4][3] = 9; dp[4][4] = 3; for(int i = 5; i <= n; ++i){ dp[i][0] = (1 + 2 * dp[i-1][0]) % mod; dp[i][1] = (dp[i-1][0] + 2 * dp[i-1][1]) % mod; dp[i][2] = (1 + dp[i-1][2]) % mod; dp[i][3] = (dp[i-1][0] + dp[i-1][2] + 2 * dp[i-1][3]) % mod; dp[i][4] = (dp[i-1][1] + dp[i-1][3] + 2 * dp[i-1][4]) % mod; } cout << dp[n][4] << endl; } }
状压DP:
#pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #include <iostream> #include <cstring> #include <set> #include <queue> #include <algorithm> #include <vector> #include <map> #include <cctype> #include <cmath> #include <stack> #define frer freopen("in.txt", "r", stdin) #define frew freopen("out.txt", "w", stdout) using namespace std; typedef long long LL; typedef pair<int, int> P; const int INF = 0x3f3f3f3f; const double inf = 0x3f3f3f3f3f3f; const double PI = acos(-1.0); const double eps = 1e-8; const int maxn = 1e3 + 5; const int mod = 1e9 + 7; const int dr[] = {-1, 1, 0, 0}; const int dc[] = {0, 0, 1, -1}; const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"}; int n, m; const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; inline int Min(int a, int b){ return a < b ? a : b; } inline int Max(int a, int b){ return a > b ? a : b; } inline LL Min(LL a, LL b){ return a < b ? a : b; } inline LL Max(LL a, LL b){ return a > b ? a : b; } inline bool is_in(int r, int c){ return r >= 0 && r < n && c >= 0 && c < m; } LL dp[maxn][(1<<4)+1]; int main(){ while(cin >> n){ memset(dp, 0, sizeof dp); dp[0][0] = 1; for(int i = 0; i < n; ++i){ for(int j = 0; j < 16; ++j){ if(!dp[i][j]) continue; if(!(j & 2) && i) dp[i+1][j|1] = (dp[i+1][j|1] + dp[i][j]) % mod; dp[i+1][j|2] = (dp[i+1][j|2] + dp[i][j]) % mod; if(!(j & 8)) dp[i+1][j|4] = (dp[i+1][j|4] + dp[i][j]) % mod; dp[i+1][j|8] = (dp[i+1][j|8] + dp[i][j]) % mod; } } cout << dp[n][15] << endl; } return 0; }
组合数学+暴力枚举:
#pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #include <iostream> #include <cstring> #include <set> #include <queue> #include <algorithm> #include <vector> #include <map> #include <cctype> #include <cmath> #include <stack> #define frer freopen("in.txt", "r", stdin) #define frew freopen("out.txt", "w", stdout) using namespace std; typedef long long LL; typedef pair<int, int> P; const int INF = 0x3f3f3f3f; const double inf = 0x3f3f3f3f3f3f; const double PI = acos(-1.0); const double eps = 1e-8; const int maxn = 1e3 + 5; const int mod = 1e9 + 7; const int dr[] = {-1, 1, 0, 0}; const int dc[] = {0, 0, 1, -1}; const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"}; int n, m; const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; inline int Min(int a, int b){ return a < b ? a : b; } inline int Max(int a, int b){ return a > b ? a : b; } inline LL Min(LL a, LL b){ return a < b ? a : b; } inline LL Max(LL a, LL b){ return a > b ? a : b; } inline bool is_in(int r, int c){ return r >= 0 && r < n && c >= 0 && c < m; } LL c[maxn][maxn]; void init(){ for(int i = 0; i < n; ++i) c[i][0] = c[i][i] = 1; for(int i = 2; i < n; ++i) for(int j = 1; j < i; ++j) c[i][j] = (c[i-1][j] + c[i-1][j-1]) % mod; } int main(){ while(cin >> n){ init(); LL ans = 0; for(int i = 2; i < n-1; ++i) ans = (ans + (c[n-1][i] * (i-1) * (n-i-1)) % mod) % mod; cout << ans << endl; } return 0; }
推公式:
#pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #include <iostream> #include <cstring> #include <set> #include <queue> #include <algorithm> #include <vector> #include <map> #include <cctype> #include <cmath> #include <stack> #define frer freopen("in.txt", "r", stdin) #define frew freopen("out.txt", "w", stdout) using namespace std; typedef long long LL; typedef pair<int, int> P; const int INF = 0x3f3f3f3f; const double inf = 0x3f3f3f3f3f3f; const double PI = acos(-1.0); const double eps = 1e-8; const int maxn = 1e3 + 5; const int mod = 1e9 + 7; const int dr[] = {-1, 1, 0, 0}; const int dc[] = {0, 0, 1, -1}; const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"}; int n, m; const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; inline int Min(int a, int b){ return a < b ? a : b; } inline int Max(int a, int b){ return a > b ? a : b; } inline LL Min(LL a, LL b){ return a < b ? a : b; } inline LL Max(LL a, LL b){ return a > b ? a : b; } inline bool is_in(int r, int c){ return r >= 0 && r < n && c >= 0 && c < m; } LL quick_pow(LL a, LL b){ LL ans = 1; while(b){ if(b & 1) ans = (ans * a) % mod; b >>= 1; a = (a * a) % mod; } return ans; } int main(){ while(cin >> n){ LL ans = (n * n - 5 * n + 4) % mod; ans = (ans * quick_pow(2LL, n-3) + n - 1) % mod; cout << ans << endl; } return 0; }
矩阵快速幂:
#pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #include <iostream> #include <cstring> #include <set> #include <queue> #include <algorithm> #include <vector> #include <map> #include <cctype> #include <cmath> #include <stack> #define frer freopen("in.txt", "r", stdin) #define frew freopen("out.txt", "w", stdout) using namespace std; typedef long long LL; typedef pair<int, int> P; const int INF = 0x3f3f3f3f; const double inf = 0x3f3f3f3f3f3f; const double PI = acos(-1.0); const double eps = 1e-8; const int maxn = 1e3 + 5; const int mod = 1e9 + 7; const int dr[] = {-1, 1, 0, 0}; const int dc[] = {0, 0, 1, -1}; const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"}; int n, m; const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; inline int Min(int a, int b){ return a < b ? a : b; } inline int Max(int a, int b){ return a > b ? a : b; } inline LL Min(LL a, LL b){ return a < b ? a : b; } inline LL Max(LL a, LL b){ return a > b ? a : b; } inline bool is_in(int r, int c){ return r >= 0 && r < n && c >= 0 && c < m; } struct Matrix{ LL a[6][6]; }; Matrix mul(Matrix x, Matrix y){ Matrix ans; memset(ans.a, 0, sizeof ans.a); for(int i = 0; i < 6; ++i){ for(int j = 0; j < 6; ++j){ for(int k = 0; k < 6; ++k){ ans.a[i][j] += (x.a[i][k] * y.a[k][j]) % mod; } ans.a[i][j] %= mod; } } return ans; } Matrix quick_pow(Matrix x, int b){ Matrix ans; memset(ans.a, 0, sizeof ans.a); for(int i = 0; i < 6; ++i) ans.a[i][i] = 1; while(b){ if(b & 1) ans = mul(ans, x); b >>= 1; x = mul(x, x); } return ans; } int main(){ Matrix x, y; memset(x.a, 0, sizeof x.a); memset(y.a, 0, sizeof y.a); x.a[3][3] = x.a[0][0] = x.a[1][0] = x.a[2][1] = x.a[3][0] = x.a[4][1] = x.a[4][3] = x.a[5][2] = x.a[5][4] = x.a[5][5] = 1; x.a[1][1] = x.a[4][4] = x.a[5][5] = x.a[2][2] = 2; y.a[0][0] = 1; while(cin >> n){ Matrix ans = mul(quick_pow(x, n-1), y); cout << ans.a[5][0] << endl; } return 0; }
CCF 201312-4 有趣的数 (数位DP, 状压DP, 组合数学+暴力枚举, 推公式, 矩阵快速幂)
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原文地址:http://www.cnblogs.com/dwtfukgv/p/5818722.html