ACM 组合数学

//C(n,r) int c(int n,int r){ int c=1; for(int i=0;i<r;i++) c=c*(n-i)/(i+1); return c; } //排列生成函数 next_permutation string str; cin >> str; sort(str.begin(), str.end()); cout << str << endl; while(next_permutation(str.begin(), str.end())){ cout << str << endl; } //母函数模板 const int maxn = 10010; int c1[maxn], c2[maxn]; int main() { int num; int i,j,k; while(~scanf("%d", &num)){ for(int i = 0; i <= num; i++){ c1[i] = 1; c2[i] = 0; } for(int i = 2; i <= num; i++){ for(int j = 0; j <= num; j++){ for(int k = 0; k+j <= num; k += i){ c2[j+k] += c1[j]; } } for(int j = 0; j <= num; j++){ c1[j] = c2[j]; c2[j] = 0; } } printf("%d\n", c1[num]); } }