foo.cc: In function 'int main()':
foo.cc:17:54: warning: left operand of comma operator has no effect [-Wunused-value]
 for(int j=0;j<=k;j++)f[j]=(sum[j+1]-sum[j,max(0,j-i+1)]+mod)%mod;
                                                      ^

正在同步测试数据，请稍后
自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。