计算x的n次方。要求时间控制在log₂n内。

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace ConsoleApplication3{    class Program    {        static void Main(string[] args)        {            const int n = 10;            for (int i = 1; i <= 5; ++i)            {                int a = exp(i, n);                int b = binexp(i, n);                Console.WriteLine(string.Format("Calc {0}, Value: {1}={2}, TestResult: {3}",                    i,                     a, b,                    a == b                    ));            }        }        static int exp(int a, int n)        {            if (n == 0) return 1;            return a * exp(a, n - 1);        }        static int binexp(int a, int n)        {            if (n == 0) return 1;            else if (n % 2 == 0)            {                int b = binexp(a, n / 2);                return b * b;            }            return a * binexp(a, n - 1);        }    }}