Problem Description
A number sequence is defined as follows:
f(1) = 1, f(2) = 1, f(n) = (A * f(n – 1) + B * f(n – 2)) mod 7.
Given A, B, and n, you are to calculate the value of f(n).
Input
The input consists of multiple test cases. Each test case contains 3 integers A, B and n on a single line (1 <= A, B <= 1000, 1 <= n <= 100,000,000). Three zeros signal the end of input and this test case is not to be processed.
Output
For each test case, print the value of f(n) on a single line.
Sample Input
1 1 3
1 2 10
0 0 0
Sample Output
2
5
递归问题。首先要求出周期T48.然后他就华丽丽的变成了一道数学题。嗯……
#include
int main(){
long a,b,n,i,func[100];
while(scanf(“%ld%ld%ld”,&a,&b,&n) && a!=0){
func[1]=func[2]=1;
for(i=3;i<=48;i++)
func[i]=(a*func[i-1]+b*func[i-2])%7;
printf("%ldn",func[(n>48)?n%48:n]);
}
return 0;
}
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