【LeetCode】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, 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:

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. 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: C = 100, L = 50, XXX = 30 and III = 3.

Example 5:

Input: 1994
Output: "MCMXCIV"
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.

就是把阿拉伯数字转换成罗马数字的形式。

没想到怎么转换，自己的想法很麻烦，想了好久没想出来，然后看了下讨论区。我嘞个去，没想到这么简单。直接贴代码了

class Solution {
public:
    string intToRoman(int num) {
        string kb[]={"","M","MM","MMM"};
        string hd[]={"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"};
        string dd[]={"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"};
        string ut[]={"","I","II","III","IV","V","VI","VII","VIII","IX"};
        
        string r = kb[num/1000]+hd[(num%1000)/100]+dd[(num%100)/10]+ut[num%10];
        return r;
    }
};

自己还是欠缺一点发散思维，别被常规的思路禁锢了。要打破常规

【LeetCode】12. Integer to Roman

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