poj[1001] Exponentiation

最新推荐文章于 2019-08-26 12:24:44 发布

原创最新推荐文章于 2019-08-26 12:24:44 发布 · 271 阅读

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本文介绍了一种实现特定格式浮点数乘方运算的C++算法。该算法能够处理包含小数部分的数字，并通过逐位相乘的方式完成乘方计算。文章详细展示了如何解析输入字符串、进行乘法操作并输出最终结果。

#include<iostream>
#include<string>

using namespace std;

int main(int argc, char* argv[])
{
	string r;
	int n, dian;
	const int len = 160;
	short result[len], jieguo[len], chengshu[6];
	while (cin>>r>>n)
	{
		int len1 = 0;
		for (int i = 0; i < len; ++i)jieguo[i] = result[i] = 0;
		for (int i = 0; i < 6; ++i)chengshu[i] = 0;
		dian = 0;
		string::size_type pos = r.find(".");
		if (pos != string::npos)dian = (5 - pos)*n;
		for (int i = 5, j = 0; i >= 0; --i)
		{
			if (r[i] != '.')
			{
				jieguo[j] = result[j] = chengshu[j] = r[i] - '0';
				++j;
			}
		}
		while (n>=2)
		{
			--n;
			for (int i = 0; i < len; ++i)result[i] = 0;
			for (int i = 0; i < 5; ++i)
			{
				int c;
				for (int j = 0; j < len; ++j)
				{
					if (chengshu[i] == 0)break;
					c = chengshu[i] * jieguo[j];
					result[i + j] += c;
					for (int t = i + j; result[t] > 9; ++t)
					{
						result[t + 1] += result[t] / 10;
						result[t] = result[t] % 10;

					}
				}
			}
			for (int i = 0; i < len; ++i) jieguo[i]=result[i];

		}
		/*int firstindex = -1;
		for (int i = len - 1; i >= dian; --i)
		{
			if (result[i] > 0)
			{
				firstindex = i;
				break;
			}
		}
		int lastindex = -1;
		for (int i = 0; i < dian; ++i)
		{
			if (result[i] > 0)
			{
				lastindex = i;
				break;
			}
		}
		if (firstindex != -1)
		{
			while (firstindex >= dian)
			{
				cout << result[firstindex];
				--firstindex;
			}
			
		}
		if (lastindex != -1)
		{
			cout << '.';
			--dian;
			while (dian>=lastindex)
			{
				cout << result[dian];
				--dian;
			}
		}
		cout << endl;
		*/
		int firstindex = -1;
		for (int i = len - 1; i >= dian; --i)
		{
		  if (jieguo[i] > 0)
		   {
		     firstindex = i;
		     break;
		   }
		}
		int lastindex = -1;
		for (int i = 0; i < dian; ++i)
		{
		  if (jieguo[i] > 0)
		  {
		     lastindex = i;
		     break;
		   }
		}
		if (firstindex != -1)
		{
		   while (firstindex >= dian)
		   {
		     cout << jieguo[firstindex];
		     --firstindex;
		    }

		}
		if (lastindex != -1)
		{
		cout << '.';
		--dian;
		while (dian>=lastindex)
		{
		cout << jieguo[dian];
		--dian;
		}
		}
		cout << endl;
		


	}

	return 0;
}

参见：http://blog.youkuaiyun.com/shaw1994/article/details/12273987