Trie

(13) Roman to Integer

I can be placed before V (5) and X (10) to make 4 and 9.
X can be placed before L (50) and C (100) to make 40 and 90.
C can be placed before D (500) and M (1000) to make 400 and 900.

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class Solution:
def romanToInt(self,s):
translation={
"I":1,
"V":5,
"X":10,
"L":50,
"C":100,
"D":500,
"M":1000
}
number=0
s = s.replace("IV", "IIII").replace("IX", "VIIII")
s = s.replace("XL", "XXXX").replace("XC", "LXXXX")
s = s.replace("CD", "CCCC").replace("CM", "DCCCC")
for char in s:
number +=translation[char]
return number

2.Medium

(139)Word Break

(208)Implement Trie (Prefix Tree)