Problem 12: Integer to Roman
思路
像做除法运算一样,提前把 千位数,百位数,个位数都存好,然后一位一位地求出来
public class Solution {
public String intToRoman(int num) {
String M[] = {"", "M", "MM", "MMM"}; //1000, 2000, 3000
String C[] = {"", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"}; //100,200,300,...,900
String X[] = {"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"}; //10,20,...,90
String I[] = {"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"}; //1,2,3,...,9
return M[num / 1000] + C[num % 1000 / 100] + X[num % 100 / 10] + I[num % 10];
}
}
易错点
每个String数组开始都有一个“”空字符串,这个位置是给0预备的
M[num / 1000] + C[num % 1000 / 100] + X[num % 100 / 10] + I[num % 10]
直接想的时候有时候会出现一些小的错误,如果能直接举例子,就会好很多了。eg: 3560,然后自己手动拿手除一下
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