ural 1044 Lucky Tickets. Easy!

又是个大水题.....甚至到了可以打表的程度......

#include<iostream>using namespace std;int A[5][45];int tot,n;int main(){int i,j,k;scanf("%d",&n);n/=2;A[0][0]=1;for(i=0;i<n;i++)for(k=0;k<=i*9;k++)for(j=0;j<10;j++)A[i+1][k+j]+=A[i][k];for(i=0;i<=n*9;i++)tot+=A[n][i]*A[n][i];printf("%d/n",tot);return 0;}/*I: 2 O: 10I: 4 O: 670I: 6 O: 55252I: 8 O: 4816030*/