所以为啥要写来着...........
T1
直接枚举大于等于$n$的所有数,暴力分解判断即可
复杂度$O(10n log n)$
#include <cstdio> #include <iostream> using namespace std; #define sid 15 #define ri register int int n, k, D[sid]; int main() { int x, flag; cin >> n >> k; for(ri i = 1; i <= k; i ++) { cin >> x; D[x] = 1; } for(ri i = n; i; i ++) { x = i; flag = 0; while(x) { if(D[x % 10]) { flag = 1; break; } x /= 10; } if(!flag) { printf("%d ", i); break; } } return 0; }
T2
把第$B$列单独拿出来讨论转移即可
复杂度$O(H)$
#include <cstdio> #include <iostream> using namespace std; #define sid 200050 #define ri register int #define mod 1000000007 int fac[sid], inv[sid]; int H, W, A, B; void Init_C() { fac[0] = fac[1] = 1; inv[0] = inv[1] = 1; for(ri i = 2; i <= 200000; i ++) fac[i] = 1ll * fac[i - 1] * i % mod; for(ri i = 2; i <= 200000; i ++) inv[i] = 1ll * (mod - mod / i) * inv[mod % i] % mod; for(ri i = 2; i <= 200000; i ++) inv[i] = 1ll * inv[i - 1] * inv[i] % mod; } int C(int n, int m) { if(m > n) return 0; return 1ll * fac[n] * inv[m] % mod * inv[n - m] % mod; } int way(int x1, int y1, int x2, int y2) { return C(x2 - x1 + y2 - y1, x2 - x1); } int main() { Init_C(); cin >> H >> W >> A >> B; int ans = 0, sum = 0; for(ri i = 1; i <= H - A; i ++) ans = (ans + 1ll * way(1, 1, B, i) * way(B + 1, i, W, H) % mod) % mod; printf("%d ", ans); return 0; }
T3
神奇状压.......
一开始没怎么想直接打了错误的$dp$....没过样例才意识到什么
正着计数不好计数,考虑反面,求解不存在连续区间和为$X, Y, Z$的数量
把$X, Y, Z$状压成为一种状态,当在末尾插入数字时,直接把状态前移,前面的数字会自动前移.....
然后暴力转移即可,复杂度$O(2^{17} * 40)$
#include <cstdio> #include <cstring> #include <iostream> using namespace std; #define ri register int #define mod 1000000007 int bit[60]; int N, x, y, z; int f[43][140005]; int main() { cin >> N >> x >> y >> z; for(ri i = 0; i <= 25; i ++) bit[i] = 1 << i; int ans = 1; for(ri i = 1; i <= N; i ++) ans = 1ll * ans * 10 % mod; f[0][0] = 1; int gg = bit[z - 1] | bit[y + z - 1] | bit[x + y + z - 1]; int lim = bit[x + y + z] - 1; for(ri i = 1; i <= N; i ++) for(ri S = 0; S <= lim; S ++) for(ri v = 1; v <= 10; v ++) { int T = (S << v) | bit[v - 1]; T &= lim; if((T & gg) != gg) f[i][T] = (f[i][T] + f[i - 1][S]) % mod; } for(ri S = 0; S <= lim; S ++) if((S & gg) != gg) ans = (ans - f[N][S] + mod) % mod; printf("%d ", ans); return 0; }
T4
留坑...
咕咕咕咕咕咕咕...