#include <algorithm>
#include <cstdio>
#include <functional>
#include <map>
#include <vector>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define VAR(v,w) __typeof(w) v=(w)
#define ALL(c) (c).begin(),(c).end()
#define SD second
#define INT(x) int x; scanf("%d", &x)
typedef long long LL;
typedef vector<int> VI;
const int mod = 1000000007;
int k, revk;
map<VI, int> cache;
inline LL MODL(LL a,LL b) {
return a >= 0 ? a % b : b + ((a + 1) % b) - 1;
}
LL EXTEUC(LL a, LL b, LL& x, LL& y) {
x = 1;
y = 0;
LL x1 = 0, y1 = 1;
while (b != 0) {
LL t = b;
LL q = a / b;
b = a % b;
a = t;
t = x1;
x1 = x - q * x1;
x = t;
t = y1;
y1 = y - q * y1;
y = t;
}
return a;
}
LL REVM(LL a, LL m) {
LL x, y;
EXTEUC(m, a, x, y);
return MODL(y, m);
}
int go(const VI& v) {
VAR(it,cache.find(v));
if (it != cache.end()) return it->SD;
int r = 0;
FOR(d,1,k+1) {
VI w(v);
if (w[0] <= d) break;
w[0] -= d;
sort(ALL(w), greater<int>());
r = (r + go(w)) % mod;
}
r = LL(r) * revk % mod;
r = (r + 1) % mod;
cache[v] = r;
return r;
}
int main() {
INT(n);
INT(k1);
INT(m);
k = k1;
revk = REVM(k, mod);
printf("%d\n", go(VI(n, m)));
}
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 | #include <algorithm> #include <cstdio> #include <functional> #include <map> #include <vector> using namespace std; #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define VAR(v,w) __typeof(w) v=(w) #define ALL(c) (c).begin(),(c).end() #define SD second #define INT(x) int x; scanf("%d", &x) typedef long long LL; typedef vector<int> VI; const int mod = 1000000007; int k, revk; map<VI, int> cache; inline LL MODL(LL a,LL b) { return a >= 0 ? a % b : b + ((a + 1) % b) - 1; } LL EXTEUC(LL a, LL b, LL& x, LL& y) { x = 1; y = 0; LL x1 = 0, y1 = 1; while (b != 0) { LL t = b; LL q = a / b; b = a % b; a = t; t = x1; x1 = x - q * x1; x = t; t = y1; y1 = y - q * y1; y = t; } return a; } LL REVM(LL a, LL m) { LL x, y; EXTEUC(m, a, x, y); return MODL(y, m); } int go(const VI& v) { VAR(it,cache.find(v)); if (it != cache.end()) return it->SD; int r = 0; FOR(d,1,k+1) { VI w(v); if (w[0] <= d) break; w[0] -= d; sort(ALL(w), greater<int>()); r = (r + go(w)) % mod; } r = LL(r) * revk % mod; r = (r + 1) % mod; cache[v] = r; return r; } int main() { INT(n); INT(k1); INT(m); k = k1; revk = REVM(k, mod); printf("%d\n", go(VI(n, m))); } |
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