leetcode-12. Integer to Roman

leetcode-12. Integer to Roman

题目：

Given an integer, convert it to a roman numeral.

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

主要思路就是根据10*,90*,50*,40*,这几个点分段处理就行。没有特别需要注意的。

public class Solution {
    public String intToRoman(int num) {
        StringBuilder sb = new StringBuilder();
            if(num>999){
                int M = num/1000;
                num -= M*1000;
                while(M-- !=0){
                    sb.append("M");
                }
            }
            if(num > 899){
                num -=900;
                sb.append("CM");
            }
            if(num > 499){
                num -= 500;
                int C = num/100;
                num -= C * 100;
                sb.append("D");
                while(C-- != 0)
                    sb.append("C");
            }
            if(num >399){
                num -= 400;
                sb.append("CD");
            }
            if(num > 99){
                int C = num/100;
                num -= C * 100;
                while(C-- != 0)
                    sb.append("C");
            }
            if(num > 89){
                num -= 90;
                sb.append("XC");
            }
            if(num > 49){
                num -= 50;
                sb.append("L");
                int X = num/10;
                num -= X * 10;
                while(X-- != 0){
                    sb.append("X");
                }

            }
            if(num > 39){
                num -= 40;
                sb.append("XL");
            }
            if(num > 9){
                int X = num/10;
                num -= X * 10;
                while(X-- != 0)
                    sb.append("X");
            }
            if(num > 8){
                num -= 9;
                sb.append("IX");
            }
            if(num > 4){
                num -= 5;
                sb.append("V");
                while(num-- != 0)
                    sb.append("I");
            }
            if(num > 3){
                num -= 4;
                sb.append("IV");
            }
            if(num > 0){
                while(num-- != 0)
                sb.append("I");
            }
        return sb.toString();
    }
}