Roman to Integer (Difficulty: Easy)
- This is an easy question. However, the important takeaway is that slicing string
s = s[2:]is much slower than index manipulating
This is because left parts of string need to be taken down by garbage collection. Otherwise, it will cause memory leak.
class Solution:
def romanToInt(self, s: str) -> int:
symbol_value = {
"I": 1, "IV": 4, "V": 5, "IX": 9,
"X": 10, "XL": 40, "L": 50, "XC": 90,
"C": 100, "CD": 400, "D": 500, "CM": 900,
"M": 1000
}
num = 0
i = 0
while i < len(s):
c2 = s[i:i+2]
if c2 in symbol_value:
num += symbol_value[c2]
i += 2
# s = s[2:] this operation is slower than index-based method
# b/c this requires memory operations such as garbage collection
else:
c1 = s[i]
num += symbol_value[c1]
i += 1
# s = s[1:]
return num