USACO2.3 五道題目

【prefix】

/* ID: wangqia6 TASK: prefix LANG: C++ */ #include <fstream> #include <string> #include <cstring> using namespace std; const long PNUM = 99901; const long LMAX = 200005; ifstream cin ("prefix.in"); ofstream cout ("prefix.out"); bool hash[PNUM],f[LMAX]; long list_tot = 0,len,ans; string data; void prework() { memset(hash,0,sizeof(hash)); memset(f,0,sizeof(f)); } long calc_hash(string x) { long len = x.size(),tmp = 0; for (long i = 0; i < len; i++) tmp = ((tmp << 2) + long (x[i])) % PNUM; return tmp; } void initdata() { string tmp; cin >> tmp; while (tmp != ".") { hash[calc_hash(tmp)] = true; cin >> tmp; } cin >> data; while (cin >> tmp) data += tmp; len = data.size(); cin.close(); return; } void solve() { long big = len > 10 ? 10 : len,k,j,i; for (j = 1; j <= big; j++) { string tmp (data,0,j); k = calc_hash(tmp); if (hash[k]) { f[j - 1] = true; ans = j; } } for (i = ans; i < len; i++) if (! f[i]) { for (j = 1; j <= 10; j++) if (i - j < 0) break; else if (! f[i - j]) continue; else { string tmp (data,i + 1 - j,j); k = calc_hash(tmp); if (hash[k]) { f[i] = true; ans = i + 1; break; } } } return; } void outitdata() { cout << ans << endl; cout.close(); return; } int main() { prework(); initdata(); solve(); outitdata(); return 0; }

 

【cow pedigrees】

/* ID: wangqia6 TASK: nocows LANG: C++ */ #include <fstream> #include <cstring> using namespace std; const long PNUM = 9901; const long NMAX = 205; const long HMAX = 105; long f[NMAX][HMAX]; long n,h,i,j,k; int main() { ifstream cin ("nocows.in"); ofstream cout ("nocows.out"); cin >> n >> h; memset(f,0,sizeof(f)); for (i = 1; i <= h; i++) f[1][i] = 1; for (i = 3; i <= n; i+= 2) for (j = 1; j <= h; j++) for (k = 1; k <= i - 2; k++) f[i][j] = (f[i][j] + f[k][j - 1] * f[i - 1 - k][j - 1]) % PNUM; cout << (PNUM + f[n][h] - f[n][h - 1]) % PNUM << endl; cin.close(); cout.close(); return 0; }

 

【zero sum】

/* ID: wangqia6 TASK:zerosum LANG: C++ */ #include <fstream> using namespace std; ifstream cin ("zerosum.in"); ofstream cout ("zerosum.out"); int n,plan[10]; void outit() { for (int i = 1; i < n; i++) { cout << i; if (plan[i] == 1) cout << ' '; else if (plan[i] == 2) cout << '+'; else cout << '-'; } cout << n << endl; return; } void dfs(int dep,long now_ans,long now_num,bool flag) { if (dep == n) { if (flag) now_ans += now_num; else now_ans -=now_num; if (now_ans == 0) outit(); return; } for (int k = 1; k <= 3; k++) { plan[dep] = k; if (k == 1) dfs(dep + 1,now_ans,now_num * 10 + dep + 1,flag); else if ((k == 2) && (flag)) dfs(dep + 1,now_ans + now_num,dep + 1,true); else if ((k == 2) && (! flag)) dfs(dep + 1,now_ans - now_num,dep + 1,true); else if ((k == 3) && (flag)) dfs(dep + 1,now_ans + now_num,dep + 1,false); else if ((k == 3) && (! flag)) dfs(dep + 1,now_ans - now_num,dep + 1,false); } return; } int main() { cin >> n; dfs(1,0,1,true); cin.close(); cout.close(); return 0; }

 

【money systems】

/* ID: wangqia6 TASK: money LANG: C++ */ #include <fstream> #include <cstring> using namespace std; long long f[10005]; int main() { ifstream cin ("money.in"); ofstream cout ("money.out"); memset(f,0,sizeof(f)); f[0] = 1; long m,n,a,i,j; cin >> m >> n; for (i = 1; i <= m; i++) { cin >> a; for (j = a; j <= n; j++) f[j] += f[j - a]; } cout << f[n] << endl; cin.close(); cout.close(); return 0; }

 

【controlling companies】

/* ID: wangqia6 TASK: concom LANG: C++ */ #include <fstream> #include <cstring> using namespace std; const int NMAX = 105; ifstream cin ("concom.in"); ofstream cout ("concom.out"); int data[NMAX][NMAX]; long head = 0,tail = -1; bool vis[NMAX][NMAX]; struct { int x,y; } que[NMAX * NMAX]; void push(int a,int b) { if ((a == b) || (vis[a][b])) return; vis[a][b] = true; tail ++; que[tail].x = a; que[tail].y = b; return; } int main() { int n; cin >> n; memset(vis,0,sizeof(vis)); memset(data,0,sizeof(data)); int i,j,k,a,b,w; for (i = 0; i < n; i++) { cin >> a >> b >> w; data[a][b] = w; if (w > 50) push(a,b); } while (head <= tail) { i = que[head].x; j = que[head].y; for (k = 1; k < NMAX; k++) { data[i][k] += data[j][k]; if (data[i][k] > 50) push(i,k); } head++; } for (i = 1; i < NMAX; i++) for (j = 1; j < NMAX; j++) if (vis[i][j]) cout << i << ' ' << j << endl; return 0; }