九度 oj 题目1081：递推数列

http://ac.jobdu.com/problem.php?pid=1081

参考了（照抄了）http://blog.csdn.net/zxasqwedc/article/details/8763967 

#include <stdio.h>
#include <cstdlib>
#include <cstring>
#define LL long long

static LL a0,a1,p,q,k;

typedef struct matrix{
LL a[2][2];
} Matrix;

Matrix multiply(Matrix m1, Matrix m2){
Matrix ret ;
ret.a[0][0] = ret.a[0][1] = ret.a[1][0] = ret.a[1][1] = 0;
for (int i = 0; i < 2; ++i) {
for (int j = 0; j < 2; ++j) {
for (int t = 0; t < 2; ++t) {
ret.a[i][j] += (m1.a[i][t] * m2.a[t][j])%10000;
}
}
}
return ret;
}

Matrix matrixPow(Matrix mat, LL n){
Matrix ret;
ret.a[0][0] = 1,ret.a[1][0] = 0,ret.a[0][1]=0,ret.a[1][1] = 1;
if(n == 0) return ret;
else if( n==1 ) return mat;
else{
if(n&1){
ret = matrixPow(mat,n/2);
ret = multiply(ret, ret);
ret = multiply(mat,ret);
return ret;
}else{
ret = matrixPow(mat,n/2);
ret = multiply(ret,ret);
return ret;
}
}
}

int main(){
while(scanf("%lld %lld %lld %lld %lld",&a0,&a1,&p,&q,&k)!=EOF){
if(k==0) printf("%lld\n" ,a0);
else if(k==1) printf("%lld\n" ,a1);
else{
Matrix m;
m.a[0][0] = 0,m.a[0][1] = 1,m.a[1][0] = q,m.a[1][1] = p;
Matrix ret = matrixPow(m,k-1);
printf("%lld\n",(ret.a[1][0]*a0+ret.a[1][1]*a1)%10000 );
}
}
}