因为每个人都是无编号且每次随机选。
所以可以考虑将所有人编号,按照编号从小到大选。
定义 f[i][j] 表示第 i 个人没 si 且被攻击了 j 次,那么可以很容易列出状态转移方程。
code:
#include <bits/stdc++.h> #define int long long using namespace std; const int maxn = 2005, mod = 258280327; int f[maxn][maxn], g[maxn], T; inline int read() { int w = 0, f = 1; char ch = getchar(); while (ch < '0' or ch > '9') { if (ch == '-') f = -f; ch = getchar(); } while (ch >= '0' and ch <= '9') w = w * 10 + ch - '0', ch = getchar(); return w * f; } inline int qpow(int x, int y) { int cnt = 1, basic = x; while (y) { if (y & 1) cnt = cnt * basic % mod; basic = basic * basic % mod, y >>= 1; } return cnt; } signed main() { T = read(); while (T--) { int n = read(), x = read(), y = read(); int ny = qpow(y, mod - 2); for (int i = 0; i <= n; i++) for (int j = 0; j <= n; j++) f[i][j] = 0; for (int i = 0; i <= n; i++) g[i] = 0; f[1][0] = 1; g[0] = 1; for (int i = 1; i <= n; i++) g[i] = g[i - 1] * (y - x) % mod * ny % mod; for (int i = 2; i <= n; i++) { for (int j = 0; j < n; j++) { f[i][j] = f[i - 1][j] * ((1 - g[j]) % mod + mod) % mod; if (j) f[i][j] = (f[i][j] + f[i - 1][j - 1] * g[j] % mod) % mod; } } for (int j = 0; j < n; j++) { int ans = 0; for (int i = 1; i <= n; i++) ans = (ans + f[i][j]) % mod; printf("%lld ", ans * qpow(n, mod - 2) % mod); } printf(" "); } return 0; }