Integer to Roman (M)
題目
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, two is written as II in Roman numeral, just two one's added together. Twelve is written as, XII, which is simply X + II. The number twenty seven 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:
Ican be placed beforeV(5) andX(10) to make 4 and 9.Xcan be placed beforeL(50) andC(100) to make 40 and 90.Ccan be placed beforeD(500) andM(1000) to make 400 and 900.
Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.
Example 1:
Input: 3
Output: "III"
Example 2:
Input: 4
Output: "IV"
Example 3:
Input: 9
Output: "IX"
Example 4:
Input: 58
Output: "LVIII"
Explanation: L = 50, V = 5, III = 3.
Example 5:
Input: 1994
Output: "MCMXCIV"
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.
題意
將整數轉化為指定格式的羅馬數字，
思路
- 直接打表，將每一位數字對應的羅馬數字記錄下來，
- 依次減去[1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]，并轉化為羅馬數字添加到字串中，
代碼實作
Java
打表
class Solution {
public String intToRoman(int num) {
String[] single = {"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"};
String[] tens = {"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"};
String[] hundreds = {"", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"};
String[] thousands = {"", "M", "MM", "MMM"};
return thousands[num / 1000] + hundreds[(num % 1000) / 100] + tens[(num % 100) / 10] + single[num % 10];
}
}
減法
class Solution {
public String intToRoman(int num) {
String ans = "";
int[] numeral = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
String[] rome = {"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};
for (int i = 0; i < numeral.length; i++) {
int count = num / numeral[i];
num -= count * numeral[i];
while (count > 0) {
ans += rome[i];
count--;
}
}
return ans;
}
}
JavaScript
/**
* @param {number} num
* @return {string}
*/
var intToRoman = function (num) {
let res = ''
let map = new Map([
[1000, 'M'],
[900, 'CM'],
[500, 'D'],
[400, 'CD'],
[100, 'C'],
[90, 'XC'],
[50, 'L'],
[40, 'XL'],
[10, 'X'],
[9, 'IX'],
[5, 'V'],
[4, 'IV'],
[1, 'I'],
])
map.forEach((value, key) => {
res += value.repeat(Math.trunc(num / key))
num %= key
})
return res
}
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標籤：其他