Given a roman numeral, convert it to an integer.
Input is guaranteed to be within the range from 1 to 3999.
自己写的代码第一次没有AC,超时。第二遍就莫名其妙通过了
public int romanToInt(String s){
int result = 0;
char[] array = s.toCharArray();
Map<Character,Integer> roman = new HashMap<>();
roman.put('I',1);
roman.put('V',5);
roman.put('X',10);
roman.put('L',50);
roman.put('C',100);
roman.put('D',500);
roman.put('M',1000);
if (array.length==1){
return roman.get(array[0]);
}
for (int current = 1; current < array.length; current++) {
int pre = current-1;
int preint = roman.get(array[pre]);
int currentint = roman.get(array[current]);
if (preint>=currentint){
result+=preint;
}
else{
result-=preint;
}
}
result+=roman.get(array[array.length-1]);
return result;
}
附上相似代码
public static int romanToInt(String s) {
if (s == null || s.length() == 0)
return -1;
HashMap<Character, Integer> map = new HashMap<Character, Integer>();
map.put('I', 1);
map.put('V', 5);
map.put('X', 10);
map.put('L', 50);
map.put('C', 100);
map.put('D', 500);
map.put('M', 1000);
int len = s.length(), result = map.get(s.charAt(len - 1));
for (int i = len - 2; i >= 0; i--) {
if (map.get(s.charAt(i)) >= map.get(s.charAt(i + 1)))
result += map.get(s.charAt(i));
else
result -= map.get(s.charAt(i));
}
return result;
}