class Solution:
def longestCommonSubsequence(self, text1: str, text2: str) -> int:
m, n = len(text1), len(text2)
# dp 数组代表 text1 以 i-1 结尾和 text2 以 j-1 结尾的最长公共子序列长度
dp = [[0] * (m+1) for _ in range(n+1)]
for i in range(1, n+1):
for j in range(1, m+1):
if text1[j-1] == text2[i-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[n][m]
class Solution:
def maxUncrossedLines(self, nums1: List[int], nums2: List[int]) -> int:
m, n = len(nums1), len(nums2)
dp = [[0] * (m+1) for _ in range(n+1)]
for i in range(1, n+1):
for j in range(1, m+1):
if nums1[j-1] == nums2[i-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[n][m]
53. 最大子序和
1、动态规划
class Solution:
def maxSubArray(self, nums: List[int]) -> int:
# dp 代表 nums[i] 结尾时的最大子数组和为 dp[i]
dp = [0] * len(nums)
dp[0] = nums[0]
res = dp[0]
for i in range(1, len(nums)):
dp[i] = max(dp[i-1] + nums[i], nums[i])
res = max(dp[i], res)
return res
2、贪心
注意点: 先比较大小，再判断和是否小于 0
class Solution:
def maxSubArray(self, nums: List[int]) -> int:
sum1 = 0
res = float('-inf')
for num in nums:
sum1 += num
res = max(res, sum1)
if sum1 < 0:
sum1 = 0
return res