```
def minimumDeleteSum(self, s1, s2):
"""
:type s1: str
:type s2: str
:rtype: int
"""
l1, l2 = len(s1), len(s2)
dp = [[0] * (l2 + 1) for _ in range(l1 + 1)]
for i in range(l1):
for j in range(l2):
if s1[i] == s2[j]:
dp[i + 1][j + 1] = dp[i][j] + ord(s1[i])
else:
dp[i + 1][j + 1] = max(dp[i][j + 1], dp[i + 1][j])
result = sum(map(ord, s1 + s2)) - dp[l1][l2] * 2
return result
```