面试经典150题——Day18

文章目录

一、题目

12. Integer to Roman

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

Symbol Value

I 1

V 5

X 10

L 50

C 100

D 500

M 1000

For example, 2 is written as II in Roman numeral, just two one's added together. 12 is written as XII, which is simply X + II. The number 27 is written as XXVII, which is XX + V + II.

Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:

I can be placed before V (5) and X (10) to make 4 and 9.

X can be placed before L (50) and C (100) to make 40 and 90.

C can be placed before D (500) and M (1000) to make 400 and 900.

Given an integer, convert it to a roman numeral.

Example 1:

Input: num = 3

Output: "III"

Explanation: 3 is represented as 3 ones.

Example 2:

Input: num = 58

Output: "LVIII"

Explanation: L = 50, V = 5, III = 3.

Example 3:

Input: num = 1994

Output: "MCMXCIV"

Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.

Constraints:

1 <= num <= 3999

题目来源: leetcode

二、题解

由于num的范围在1~3999之间,因此可以直接使用硬编码的方式解决

cpp 复制代码
class Solution {
public:
    string intToRoman(int num) {
        string thousands[] = {"","M","MM","MMM"};
        string hundreds[] = {"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"};
        string tens[] = {"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"};
        string ones[] = {"","I","II","III","IV","V","VI","VII","VIII","IX"};
        string res = thousands[num / 1000] + hundreds[(num % 1000) / 100] + tens[(num % 100) / 10] + ones[num % 10];
        return res;
    }
};
相关推荐
YuTaoShao4 分钟前
【LeetCode 热题 100】994. 腐烂的橘子——BFS
java·linux·算法·leetcode·宽度优先
古月-一个C++方向的小白5 小时前
C++11之lambda表达式与包装器
开发语言·c++
tanyongxi667 小时前
C++ AVL树实现详解:平衡二叉搜索树的原理与代码实现
开发语言·c++
Wendy14418 小时前
【线性回归(最小二乘法MSE)】——机器学习
算法·机器学习·线性回归
拾光拾趣录8 小时前
括号生成算法
前端·算法
渣呵9 小时前
求不重叠区间总和最大值
算法
浮生带你学Java9 小时前
2025Java面试题及答案整理( 2025年 7 月最新版,持续更新)
java·开发语言·数据库·面试·职场和发展
拾光拾趣录9 小时前
链表合并:双指针与递归
前端·javascript·算法
好易学·数据结构9 小时前
可视化图解算法56:岛屿数量
数据结构·算法·leetcode·力扣·回溯·牛客网
斯是 陋室9 小时前
在CentOS7.9服务器上安装.NET 8.0 SDK
运维·服务器·开发语言·c++·c#·云计算·.net