Given an integer, convert it to a roman numeral.
Input is guaranteed to be within the range from 1 to 3999.
func intToRoman(num int) string {
var c[4][10]string=[4][10]string{
{"","I","II","III","IV","V","VI","VII","VIII","IX"},
{"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"},
{"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"},
{"","M","MM","MMM"}};
var roman string;
roman=roman+c[3][num / 1000 % 10]
roman=roman+c[2][num / 100 % 10]
roman=roman+c[1][num / 10 % 10]
roman=roman+c[0][num % 10]
return roman;
}