百度松果20231022作业

越狱

盒子与球

斯特林第二类数（用dp求）*盒子的阶乘

int dp[11][11]; //n>=k int A(int x){ int res=1; fer(i,2,x+1)res*=i; return res; } signed main(){ IOS; dp[2][1]=dp[2][2]=dp[1][1]=1; fer(i,3,11){ dp[i][1]=1; fer(j,2,i){ dp[i][j]=j*dp[i-1][j]+dp[i-1][j-1]; } dp[i][i]=1; } int n,r;cin>>n>>r; cout<<dp[n][r]*A(r); return 0; } 矩阵乘法

const int N=1e3+1,mod=1e9+7; int a[N][N],b[N][N],res[N][N]; signed main(){ IOS; int l,m,n; cin>>l>>m>>n; fer(i,0,l){ fer(j,0,m)cin>>a[i][j]; } fer(i,0,m){ fer(j,0,n){ cin>>b[i][j]; } } //result l*n fer(i,0,l){ fer(j,0,n){ fer(k,0,m){ res[i][j]+=a[i][k]*b[k][j]; } } } fer(i,0,l){ fer(j,0,n){ cout<<res[i][j]<<" "; } cout<<endl; } return 0; } 找朋友

最小的：1、1、1、1、……、n-m+1 最大的：n/m平均分，n%m平均分到每个小组里 res= C x 2 C_x^2 Cx2​

int C(int x,int k){ int res=1; for(int i=x;i>x-k;i--){ res*=i; } fer(i,2,k+1)res/=i; return res; } signed main(){ IOS; int n,m;cin>>n>>m; int res1=0,res2=0; int x=n/m; int y=n%m; //y个 C_{x+1}^2,(m-y)个C_x^2 res1=y*C(x+1,2)+(m-y)*C(x,2); res2=C(n-m+1,2); cout<<res1<<" "<<res2; return 0; } 点餐 signed main(){ IOS; int a;cin>>a; int b[3]; fer(i,0,3)cin>>b[i]; if(b[0]+b[1]+b[2]<=2*a)cout<<"YES"; else cout<<"NO"; return 0; }