class Solution(object):
def minimumDeleteSum(self, s1, s2):
"""
:type s1: str
:type s2: str
:rtype: int
"""
# mxn
m = len(s1)
n = len(s2)
dp = [[0]*(n+1) for _ in range(m+1)]
dp[0][0] = 0
psum1 = 0
for i in range(1, n+1):
psum1 += ord(s2[i-1])
dp[0][i] = psum1
psum2 = 0
for j in range(1,m+1):
psum2 += ord(s1[j-1])
dp[j][0] = psum2
for i in range(1, m+1):
for j in range(1,n+1):
if s1[i-1] == s2[j-1]:
dp[i][j] = dp[i-1][j-1]
else:
p1 = dp[i-1][j]+ord(s1[i-1])
p2 = dp[i][j-1]+ord(s2[j-1])
dp[i][j] = min(p1,p2)
return dp[-1][-1]