Vijos1603 迷宫
矩阵快速幂，答案是原矩阵的m次幂的第s行第f列
1 #include <iostream> 2 #include <cstdio> 3 #include <algorithm> 4 #include <cstring> 5 #define rep(i,l,r) for(int i=l; i<=r; i++) 6 #define clr(x,y) memset(x,y,sizeof(x)) 7 using namespace std; 8 const int maxn = 51; 9 int n,m,s,f,KPM; 10 struct matrix{ 11 int m[maxn][maxn]; 12 matrix(){ 13 clr(m,0); 14 } 15 void init(){ 16 rep(i,1,n) m[i][i] = 1; 17 } 18 matrix operator * (const matrix &y) const { 19 matrix ret; 20 rep(i,1,n) rep(j,1,n) rep(k,1,n) 21 ret.m[i][j] = (ret.m[i][j] + m[i][k] * y.m[k][j]) % KPM; 22 return ret; 23 } 24 }a; 25 inline int read(){ 26 int ans = 0, f = 1; 27 char c = getchar(); 28 while (!isdigit(c)){ 29 if (c == '-') f = -1; 30 c = getchar(); 31 } 32 while (isdigit(c)){ 33 ans = ans * 10 + c - '0'; 34 c = getchar(); 35 } 36 return ans * f; 37 } 38 matrix qpow(matrix x,int y){ 39 matrix ret, b = x; ret.init(); 40 while (y){ 41 if (y & 1) ret = ret * b; 42 b = b * b; 43 y >>= 1; 44 } 45 return ret; 46 } 47 int main(){ 48 n = read(); 49 rep(i,1,n) rep(j,1,n) a.m[i][j] = read(); 50 m = read(); s = read(); f = read(); KPM = read(); 51 a = qpow(a,m); 52 printf("%d\n",a.m[s][f]); 53 return 0; 54 }
