13. 罗马数字转整数
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class Solution
Map<Character, Integer> maps = new HashMap<>()
put(\'I\', 1);
put(\'V\', 5);
put(\'X\', 10);
put(\'L\', 50);
put(\'C\', 100);
put(\'D\', 500);
put(\'M\', 1000);
;
public int romanToInt(String s)
int sum = 0;
int val = 0;
for(int i=0;i<s.length();++i)
val = maps.get(s.charAt(i));
/**小于右边且右边存在则减
否则就是大于右边则加
*/
if( i < s.length()-1 && val < maps.get(s.charAt(i+1)))
sum = sum - val;
else
sum = sum + val;
return sum;
Leetcode 1213：整数转罗马数字-罗马数字转整数
自己从0到1的思路，仅供参考：
整数转罗马数字
// 整数转罗马数字
function intToRoman(num)
if (num <= 10)
return unit(num)
else if(num <= 100)
return unit2(num)
else if (num <= 1000)
return unit3(num)
else if (num > 1000)
return unit4(num)
function unit(num)
let I = 'I'
let V = 'V'
let X = 'X'
let result = ''
if (num <= 3)
for (let i = 0; i < num; i++)
result += I
else if (num === 4)
result = I + V
else if (num === 5)
result = V
else if (num > 5 && num < 9)
result = V
for (let i = 0; i < num - 5; i++)
result += I
else if (num === 9)
result = I + X
else if (num === 10)
result = X
return result
function unit2(num)
let X = 'X'
let L = 'L'
let C = 'C'
let result = ''
if (num < 40)
for (let i = 0; i < Math.floor(num / 10); i++)
result += X
if (num % 10)
result += unit(num % 10)
else if (num >= 40 && num < 50)
result = X + L
result += unit(num - 40)
else if (num === 50)
result = L
else if (num > 50 && num < 90)
result = L
for (let i = 0; i < Math.floor((num - 50) / 10); i++)
result += X
if (num % 10)
result += unit(num % 10)
else if (num >= 90 && num < 100)
result = X + C
result += unit(num - 90)
else if (num === 100)
result = C
return result
function unit3(num)
let C = 'C'
let D = 'D'
let M = 'M'
let result = ''
if (num < 400)
for (let i = 0; i < Math.floor(num / 100); i++)
result += C
if (num % 100)
result += unit2(num % 100)
else if (num >= 400 && num < 500)
result = C + D
result += unit2(num - 400)
else if (num === 500)
result = D
else if (num > 500 && num < 900)
result = D
for (let i = 0; i < Math.floor((num - 500) / 100); i++)
result += C
if (num % 100)
result += unit2(num % 100)
else if (num >= 900 && num < 1000)
result = C + M
result += unit2(num - 900)
else if (num === 1000)
result = M
return result
function unit4(num)
let M = 'M'
let result = ''
for (let i = 0; i < Math.floor(num / 1000); i++)
result += M
if (num % 1000)
result += unit3(num % 1000)
return result
罗马数字转整数
// 罗马数字转整数
let I = 'I'
let V = 'V'
let X = 'X'
let L = 'L'
let C = 'C'
let D = 'D'
let M = 'M'
function romanToInt(s)
let result = 0
if (s[0] === I)
result = unit1(s)
else if (s[0] === V)
result = unit2(s)
else if (s[0] === X) //
result = unit3(s)
else if (s[0] === L)
result = unit4(s)
else if (s[0] === C)
result = unit5(s)
else if (s[0] === D)
result = unit6(s)
else if (s[0] === M)
result = unit7(s)
console.log(result)
return result
// I
function unit1(s)
let result = 0
if (s.length <=3 && s[1] !== V && s[1] !== X)
result = s.length
else if (s.length === 2 && s[1] === V)
result = 4
else if (s.length === 2 && s[1] === X)
result = 9
return result
// V
function unit2(s)
let result = 0
result = 5 + (s.length -1)
return result
// X
function unit3(s)
let result = 0
let second = s.slice(1)
let third = s.slice(2)
if (s[1] === I)
return unit1(second) + 10
else if (s[1] === V)
return unit2(second) + 10
else if (s[0] === X && s[1] !== L && s[1] !== C)
return unit3(second) + 10
if (s[1] === L)
result = 40
if (s[2] === I)
result += unit1(third)
else if (s[2] === V)
result += unit2(third)
else if (s[1] === C)
result = 90
if (s[2] === I)
result += unit1(third)
else if (s[2] === V)
result += unit2(third)
return result
// L
function unit4(s)
let result = 0
let second = s.slice(1)
if (s[1] === I)
return unit1(second) + 50
else if (s[1] === V)
return unit2(second) + 50
else if (s[1] === X)
console.log('l', unit3(second),second)
return unit3(second) + 50
result = 50 + (s.length -1) * 10
return result
// C
function unit5(s)
let result = 0
let second = s.slice(1)
let third = s.slice(2)
if (s[1] === I)
return unit1(second) + 100
else if (s[1] === V)
return unit2(second) + 100
else if (s[1] === X)
return unit3(second) + 100
else if (s[1] === L)
return unit4(second) + 100
else if (s[0] === C && s[1] !== D && s[1] !== M)
return unit5(second) + 100
if (s[1] === D)
result = 400
if (s[2] === I)
result += unit1(third)
else if (s[2] === V)
result += unit2(third)
else if (s[2] === X)
result += unit3(third)
else if (s[2] === L)
result += unit4(third)
else if (s[1] === M)
result = 900
if (s[2] === I)
result += unit1(third)
else if (s[2] === V)
result += unit2(third)
else if (s[2] === X)
result += unit3(third)
else if (s[2] === L)
result += unit4(third)
return result
// D
function unit6(s)
let result = 0
let second = s.slice(1)
if (s[1] === I)
return unit1(second) + 500
else if (s[1] === V)
return unit2(second) + 500
else if (s[1] === X)
return unit3(second) + 500
else if (s[1] === L)
return unit4(second) + 500
else if (s[1] === C)
return unit5(second) + 500
result = 500 + (s.length -1) * 100
return result
// M
function unit7(s)
let result = 0
let second = s.slice(1)
if (s[1] === I)
return unit1(second) + 1000
else if (s[1] === V)
return unit2(second) + 1000
else if (s[1] === X)
return unit3(second) + 1000
else if (s[1] === L)
return unit4(second) + 1000
else if (s[1] === C) 以上是关于13. 罗马数字转整数的主要内容，如果未能解决你的问题，请参考以下文章