Leetcode-刷题笔记1-动态规划part11
目录
Leetcode 刷题笔记1 动态规划part11
leetcode 1143 最长公共子序列
难点在于保持相对顺序
class Solution:
def longestCommonSubsequence(self, text1: str, text2: str) -> int:
dp = [[0] * (len(text2) + 1) for i in range(len(text1) + 1)]
for i in range(1, len(text1) + 1):
for j in range(1, len(text2) + 1):
if text1[i - 1] == text2[j - 1]:
dp[i][j] = dp[i - 1][j - 1] + 1
else:
dp[i][j] = max(dp[i - 1][j], dp[i][j - 1])
return dp[-1][-1]leetcode 1035 不相交的线
同上，求最长公共子序列的变型
class Solution:
def maxUncrossedLines(self, nums1: List[int], nums2: List[int]) -> int:
dp = [[0] * (len(nums2) + 1) for _ in range(len(nums1) + 1)]
for i in range(1, len(nums1) + 1):
for j in range(1, len(nums2) + 1):
if nums1[i - 1] == nums2[j - 1]:
dp[i][j] = dp[i - 1][j - 1] + 1
else:
dp[i][j] = max(dp[i - 1][j], dp[i][j - 1])
return dp[-1][-1]leetcode 53 最大子数组和
class Solution:
def maxSubArray(self, nums: List[int]) -> int:
dp = [float('-inf')] * (len(nums) + 1)
dp[0] = nums[0]
for i in range(1, len(nums)):
dp[i] = max(dp[i - 1] + nums[i], nums[i])
return max(dp) leetcode 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]
return dp[-1][-1] == len(s)