Why my code is only working on the first object and the summs are not adding up?-CodePudding

Here is my code for Roman to Integer problem I can not understand why the for loop is only working on the first two elements.

class Solution(object):
def romanToInt(self, S):
    ran = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
    sum = 0
    for i in S:
        num = ran[i]
        num2 = ran[S[S.index(i)   1]]
        if num >= num2:
            sum = num   num2
        else:
            sum = num - num2
        return sum

CodePudding user response：

return will break for loop when excute put it after for loop and sumlogic is wrong

    def romanToInt(S):
 ran = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
 sum = 0
 for i in range(len(S)-1):
    num1=ran[S[i]]
    num2=ran[S[i 1]]
    if num1>=num2:
      sum=sum num1
    else:
      sum=sum-num1
 return sum ran[S[-1]]

CodePudding user response：

It's because the "return" is inside the for loop, so when the first loop ends, the program ends, to fix it just take the "return" out of your for loop.

def romanToInt(self, S):

    for i in S:
        .......
        .......

    return sum