UVA 11806 容斥原理

#include<cstdio>
#include<cstring>
#include<string>
#include<iostream>
#include<map>
#include<vector>
#include<utility>
#include<queue>
#include<deque>
#include<iomanip>
#include<set>
#include<algorithm>
#include<list>
#include<sstream>
using namespace std;
const int maxn = 511;
const int mod = 1000007;
int C[maxn+10][maxn+10];
int ans,k,n,m;
void dfs(int x,int cnt,int r,int c)
{
if(x==0)
{
if(cnt&1)
ans-=C[r*c][k];
else
ans+=C[r*c][k];
return;
}
if(x>2)
{
dfs(x-1,cnt+1,r-1,c);
dfs(x-1,cnt,r,c);
}
else
{
dfs(x-1,cnt+1,r,c-1);
dfs(x-1,cnt,r,c);
}
}
int main()
{
int i,j;
for(i=0;i<=maxn;++i) C[i][0]=C[i][i]=1;
for(i=1;i<=maxn;++i)
{
for(j=1;j<i;++j)
{
C[i][j]=(C[i-1][j-1]+C[i-1][j])%mod;
}
}
int T;
scanf("%d",&T);
for(int cas=1;cas<=T;++cas)
{
scanf("%d%d%d",&n,&m,&k);
ans=0;
dfs(4,0,n,m);
ans=(ans%mod+mod)%mod;
printf("Case %d: %d\n",cas,ans);
}
return 0;
}