求多项式的值与求幂的快速算法

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1. #include
   

2. int power(int x, int p)
   

3. {
   

4.     if(1 == p)
   

5.         return x;
   

6.     if(0 == (p % 2))
   

7.         return power(x * x, p / 2);
   

8.     else
   

9.         return power(x * x, p / 2) * x;
   

10. }
    

12. int polynomial(const int * coefficient, size_t size, int x)
    

13. {
    

14.     int sum = 0;
    

15.     for(size_t i = size - 1; i != 0; --i)
    

16.     {
    

17.         sum = x * sum + coefficient[i];
    

18.     }
    

19.     sum = x * sum + coefficient[0];
    

20.     return sum;
    

21. }
    

23. int main(int argc, char* argv[])
    

24. {
    

25.     int coeff[] = {1, 2, 3, 4};
    

26.     std::cout << polynomial(coeff, sizeof(coeff) / sizeof(int), 3) << std::endl;
    

27.     std::cout << power(5, 5) << std::endl;
    

28.     return 0;
    

29. }