Rectangle 暴力枚举大法

frog has a piece of paper divided into n rows and m columns. Today, she would like to draw a rectangle whose perimeter is not greater than k.

 

 

There are 8 (out of 9) ways when n=m=2,k=6

 

Find the number of ways of drawing.

 

 

 

枚举长度  然后算出宽度的取值范围  对宽带再进行求合

 

 #include <cstdio>
 #include <cstring>
 #include <queue>
 #include <cmath>
 #include <algorithm>
 #include <set>
 #include <iostream>
 #include <map>
 #include <stack>
 #include <string>
 #include <vector>
 #define pi acos(-1.0)
 #define eps 1e-6
 #define fi first
 #define se second
 #define lson l,m,rt<<1
 #define rson m+1,r,rt<<1|1
 #define bug         printf("******\n")
 #define mem(a,b)    memset(a,b,sizeof(a))
 #define fuck(x)     cout<<"["<<x<<"]"<<endl
 #define f(a)        a*a
 #define sf(n)       scanf("%d", &n)
 #define sff(a,b)    scanf("%d %d", &a, &b)
 #define sfff(a,b,c) scanf("%d %d %d", &a, &b, &c)
 #define pf          printf
 #define FRE(i,a,b)  for(i = a; i <= b; i++)
 #define FREE(i,a,b) for(i = a; i >= b; i--)
 #define FRL(i,a,b)  for(i = a; i < b; i++)
 #define FRLL(i,a,b) for(i = a; i > b; i--)
 #define FIN freopen("DATA.txt","r",stdin)
 #define lowbit(x)   x&-x
 #pragma comment (linker,"/STACK:102400000,102400000")

 using namespace std;
 const int maxn = 1e5 + ;
 typedef long long LL;
 LL n,m,k;
 int main() {
     while(~sfff(n,m,k)){
         k=k/;
         LL ans=;
         for (int i= ;i<=n ;i++) {
             if (k-i<=) break;
             LL  a=(n-i+);
             LL  b=min(k-i,m);
             LL  c=(m+(m-b+))*b/;
             ans+=a*c;
         }
         printf("%lld\n",ans);
     }
     return ;
 }