用dp[i][j]表示i到j的最长回文
如果i和j相等,就是dp[i+1][j-1]+2
否则i和j对结果没贡献,等于dp[i+1][j]或dp[i][j-1]
class Solution(object):
def longestPalindromeSubseq(self, s):
"""
:type s: str
:rtype: int
"""
m = len(s)
if m <= 1:
return m
dp = [[0 for i in range(m)] for j in range(m)]
for j in range(m):
dp[j][j] = 1
for i in range(j-1, -1, -1):
if s[i] == s[j]:
dp[i][j] = dp[i+1][j-1] + 2
else:
dp[i][j] = max(dp[i+1][j], dp[i][j-1])
return dp[0][m-1]
class Solution(object):
def longestPalindromeSubseq(self, s):
"""
:type s: str
:rtype: int
"""
m = len(s)
if m <= 1:
return m
dp = [[0 for i in range(m)] for j in range(m)]
for i in range(m-1,-1,-1):
dp[i][i] = 1
for j in range(i+1,m):
if s[i] == s[j]:
dp[i][j] = dp[i+1][j-1] + 2
else:
dp[i][j] = max(dp[i+1][j], dp[i][j-1])
return dp[0][m-1]
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