392.判断子序列
class Solution:
def isSubsequence(self, s: str, t: str) -> bool:
dp = [[0] * (len(t) + 1) for _ in range(len(s) + 1)]
for i in range(1, len(s) + 1):
for j in range(1, len(t) + 1):
if s[i - 1] == t[j - 1]:
dp[i][j] = dp[i - 1][j - 1] + 1
else:
dp[i][j] = dp[i][j - 1]
if dp[len(s)][len(t)] == len(s):
return True
return False
115.不同的子序列
class Solution:
def numDistinct(self, s: str, t: str) -> int:
dp = [[0] * (len(t) + 1) for _ in range(len(s) + 1)]
for i in range(len(s) + 1):
dp[i][0] = 1
for i in range(1, len(s) + 1):
for j in range(1, len(t) + 1):
if s[i - 1] == t[j - 1]:
dp[i][j] = dp[i - 1][j - 1] + dp[i - 1][j] 记住 （notdp[i][j] = dp[i - 1][j]+1）
else:
dp[i][j] = dp[i - 1][j]
return dp[len(s)][len(t)]
