【poj1579】Function Run Fun （动态规划DP递归，记忆化递归）

#include<cstdio>using namespace std;int arr[21][21][21];int fun(int a,int b,int c){if(a<=0||b<=0||c<=0) return 1;if(a>20||b>20||c>20) return arr[20][20][20];if(arr[a][b][c]!=0) return arr[a][b][c];if(a<b && b<c) return arr[a][b][c]=fun(a,b,c-1)+fun(a,b-1,c-1)-fun(a,b-1,c);return arr[a][b][c]=fun(a-1,b,c)+fun(a-1,b-1,c)+fun(a-1,b,c-1)-fun(a-1,b-1,c-1);}int main(){freopen("1.txt","r",stdin);int a,b,c;arr[20][20][20]=1048576;while(scanf("%d%d%d",&a,&b,&c)!=EOF){if(a==-1 &&b==-1&&c==-1) break;printf("w(%d, %d, %d) = %d/n",a,b,c,fun(a,b,c));}}