UVA 11149 - Power of Matrix(矩阵乘法)

UVA 11149 - Power of Matrix

#include <cstdio>
#include <cstring>

const int N = 45;

int n, k;

struct mat {
int v

;
mat() {memset(v, 0, sizeof(v));}
mat operator * (mat c) {
mat ans;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
for (int k = 0; k < n; k++) {
ans.v[i][j] = (ans.v[i][j] + v[i][k] * c.v[k][j]) % 10;
}
}
}
return ans;
}
mat operator + (mat c) {
mat ans;
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++)
ans.v[i][j] = (v[i][j] + c.v[i][j]) % 10;
return ans;
}
} A;

mat pow_mod(mat x, int k) {
mat ans;
for (int i = 0; i < n; i++) ans.v[i][i] = 1;
while (k) {
if (k&1) ans = ans * x;
x = x * x;
k >>= 1;
}
return ans;
}

mat solve(mat x, int k) {
if (k == 1) return x;
mat ans;
for (int i = 0; i < n; i++) ans.v[i][i] = 1;
if (k == 0) return ans;
ans = (ans + pow_mod(x, k>>1))* solve(x, k>>1);
if (k&1) ans = ans + pow_mod(x, k);
return ans;
}

int main() {
while (~scanf("%d%d", &n, &k) && n) {
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++) {
scanf("%d", &A.v[i][j]);
A.v[i][j] %= 10;
}
A = solve(A, k);
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++)
printf("%d%c", A.v[i][j], (j == n - 1 ? '\n' : ' '));
printf("\n");
}
return 0;
}