leetcode12.整数转罗马数字

 循环数值由大到小以此拼接就行

import java.util.AbstractMap.SimpleEntry;
import java.util.Map.Entry;

class Solution {
    // 定义罗马数字与对应数值的数组
    private static final Entry<Integer, String>[] valueSymbols = new SimpleEntry[]{
            new SimpleEntry<>(1000, "M"),
            new SimpleEntry<>(900, "CM"),
            new SimpleEntry<>(500, "D"),
            new SimpleEntry<>(400, "CD"),
            new SimpleEntry<>(100, "C"),
            new SimpleEntry<>(90, "XC"),
            new SimpleEntry<>(50, "L"),
            new SimpleEntry<>(40, "XL"),
            new SimpleEntry<>(10, "X"),
            new SimpleEntry<>(9, "IX"),
            new SimpleEntry<>(5, "V"),
            new SimpleEntry<>(4, "IV"),
            new SimpleEntry<>(1, "I")
    };

    public String intToRoman(int num) {
        StringBuilder roman = new StringBuilder();
        for (Entry<Integer, String> entry : valueSymbols) {
            int value = entry.getKey();
            String symbol = entry.getValue();
            while (num >= value) {
                num -= value;
                roman.append(symbol);
            }
            if (num == 0) {
                break;
            }
        }
        return roman.toString();
    }
}