Problem 16 - What is the sum of the digits of the number 2^1000?

最新推荐文章于 2020-05-22 16:49:08 发布

原创最新推荐文章于 2020-05-22 16:49:08 发布 · 2.4k 阅读

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本文介绍了一种计算2的1000次方后的数字各位相加的方法。通过使用`BigDecimal`类型进行精确计算，避免了大数运算中的溢出问题。文章提供了一个具体实现方案，即先计算指数结果，再逐位累加得到最终答案。

2¹⁵ = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.

What is the sum of the digits of the number 2¹⁰⁰⁰?

	/**
	 * I don't have a good idea.
	 * 
	 * I just calculate the result of 2 to the 1000th power.
	 * 
	 * Then get the summary of each digits.
	 * 
	 */
	public static int twoPower(int index) {
		BigDecimal result = BigDecimal.ONE;
		BigDecimal two = BigDecimal.ONE.add(BigDecimal.ONE);
		for (int i = 0; i < index; i++) {
			result = result.multiply(two);
		}
		String s = result.toString();
		int sum = 0;
		System.out.print(s);
		for (char c : s.toCharArray()) {
			sum += (c - '0');
		}
		return sum;
	}