zoj1163 The Staircases

#include<stdio.h>double dp[501][501];int main(){int n,i,j,k;for(i=1;i<501;i++)dp[i][0]=0;dp[0][0]=1;for(i=0;i<501;i++){for(k=1;k<=i;k++)dp[i][k]=dp[i-k][k-1]+dp[i][k-1];for(k=i+1;k<501;k++)dp[i][k]=dp[i][i];}while(~scanf("%d",&n)&&n){printf("%.0f\n",dp[n][n]-1);}return 0;}