0718.Maximum_Length_of_Repeated_Subarray.py

"""
Given two integer arrays nums1 and nums2, return the maximum length of a subarray that appears in both arrays.

 

Example 1:

Input: nums1 = [1,2,3,2,1], nums2 = [3,2,1,4,7]
Output: 3
Explanation: The repeated subarray with maximum length is [3,2,1].
Example 2:

Input: nums1 = [0,0,0,0,0], nums2 = [0,0,0,0,0]
Output: 5
 

Constraints:

1 <= nums1.length, nums2.length <= 1000
0 <= nums1[i], nums2[i] <= 100
"""

"""
dp[i][j] the max lens of repeated subarray and the subarray ended with A[i-1] and B[j-1]
dp[m][n] 最大值
"""
class Solution:
    def findLength(self, nums1: List[int], nums2: List[int]) -> int:
        m, n = len(nums1), len(nums2)
        dp = [[0] * (n+1) for _ in range(m+1)]
        max_len = 0
        for i in range(1, m+1):
            for j in range(1, n+1):
                if nums1[i-1] == nums2[j-1]:
                    dp[i][j] = dp[i-1][j-1] + 1
                    max_len = max(max_len, dp[i][j])
        
        return max_len