12. Integer to Roman

最新推荐文章于 2024-01-03 14:56:38 发布

原创最新推荐文章于 2024-01-03 14:56:38 发布 · 231 阅读

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本文介绍了一种将整数转换为罗马数字的方法，通过定义数组存储不同位数对应的罗马数字字符，利用除法和取余操作进行转换。该方法适用于1至3999之间的整数，并使用StringBuilder提高字符串拼接效率。

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Given an integer, convert it to a roman numeral.

Input is guaranteed to be within the range from 1 to 3999.

public class Solution {
	private static String M[] = {"","M","MM","MMM"};
	private static String C[] = {"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"};
	private static String X[] = {"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"};
	private static String I[] = {"","I","II","III","IV","V","VI","VII","VIII","IX"};
	public String intToRoman(int num) {
		StringBuilder roman = new StringBuilder();
		return roman.append(M[num/1000]).append(C[(num%1000)/100]).append(X[(num%100)/10]).append(I[num%10]).toString();
		//当在一个循环中将许多字符串连接在一起时，使用 StringBuilder类可以提升性能。
	}
}

之前不知道罗马数字的我是内心崩溃的，发现不难的题也做不出来。

重点提一下：当在一个循环中将许多字符串连接在一起时，使用 StringBuilder类可以提升性能。如果用String连接在一起提交的话，用时排名一下子就到很后面去了，这个方法用时打败了98%~