712) Minimum ASCII Delete Sum for Two Strings.py

class Solution:
    def minimumDeleteSum(self, s1: str, s2: str) -> int:
        prev_row = [0] * (len(s2) + 1)
        for j in range(1, len(s2) + 1):
            prev_row[j] = prev_row[j - 1] + ord(s2[j - 1])

        for i in range(1, len(s1) + 1):
            curr_row = [prev_row[0] + ord(s1[i - 1])]
            for j in range(1, len(s2) + 1):
                if s1[i - 1] == s2[j - 1]:
                    curr_row.append(prev_row[j - 1])
                else:
                    curr_row.append(min(prev_row[j] + ord(s1[i - 1]), curr_row[j - 1] + ord(s2[j - 1])))
            prev_row = curr_row

        return prev_row[-1]