Uvalive 6600 spanning trees in a secure lock pattern matrix

Link: https://icpcarchive.ecs.baylor.edu/index.php? Option = com_onlinejudge & Itemid = 8 & page = show_problem & problem = 4611

Question: Give a matrix of N * n vertices (n <= 6). Each vertex can only be connected to eight neighboring vertices and ask how many tree generation methods are available.

Idea: The question is very clear, that is, to list a matrix of the edge of each vertex, and then obtain the determinant of the submatrix. Because N is only 6, you can create a table.

Code for table creation:

# Include <algorithm> # include <cmath> # include <cstdio> # include <cstdlib> # include <cstring> # include <ctime> # include <ctype. h> # include <iostream> # include <map> # include <queue> # include <set> # include <stack> # include <string> # include <vector> # define EPS 1e-8 # define INF 0x7fffffff # define PI ACOs (-1.0) # define seed 31 // 131,1313 typedef long ll; typedef unsigned long ull; using namespace STD; # define m Od 1000 # define maxn 40 # define maxm 40 struct matrix {int n, m; Double A [maxn] [maxm]; void change (int c, int D) {n = C; M = D; For (INT I = 0; I <n; I ++) for (Int J = 0; j <m; j ++) A [I] [J] = 0;} void copy (const Matrix & X) {n = x. n; M = x. m; For (INT I = 0; I <n; I ++) for (Int J = 0; j <m; j ++) A [I] [J] = x. A [I] [J];} void build (int n) {change (N * n, n * n); For (INT I = 0; I <n * N; I ++) {if (I % n! = 0) {A [I] [I-1] =-1; A [I-1] [I] =-1; A [I] [I] ++; A [I-1] [I-1] ++;} if (I % n! = 0 & I/n! = 0) {A [I] [i-n-1] =-1; A [i-n-1] [I] =-1; A [I] [I] ++; A [i-n-1] [i-n-1] ++;} if (I % n! = 0 & I/n! = N-1) {A [I] [I + n-1] =-1; A [I + n-1] [I] =-1; A [I] [I] ++; A [I + n-1] [I + n-1] ++;} If (I/n! = N-1) {A [I] [I + N] =-1; A [I + N] [I] =-1; A [I] [I] ++; A [I + N] [I + N] ++ ;}} double det () {for (INT I = 1; I <n; I ++) {for (Int J = 0; j <I; j ++) if (a [I] [J]! = 0) {for (int K = J + 1; k <m; k ++) A [I] [k]-= (a [J] [k] * A [I] [J]/A [J] [J]); A [I] [J] = 0 ;}} double ans = 1; for (INT I = 0; I <n-1; I ++) ans * = A [I] [I]; return ans ;}}; int main () {int t; scanf ("% d", & T); matrix; a. build (t); printf ("%. 0f \ n ",. det (); Return 0 ;}

AC code:

 
Int main () {char ss [10] [40] = {"1", "16", "17745", "1064918960", "3271331573452806", "504061943351319050000000 "}; int t; scanf ("% d", & T); While (t --) {int A; scanf ("% d", & ); puts (ss [A-1]);}
 

Uvalive 6600 spanning trees in a secure lock pattern matrix