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# Ray liyunrui

Created Apr 1, 2021
View 48. Rotate Image.py
 class Solution: def rotate(self, matrix: List[List[int]]) -> None: """ Do not return anything, modify matrix in-place instead. """ m = len(matrix) n = len(matrix[0]) row_b = 0 # 0-> 1 row_e = m-1 # 2->1 col_b = 0
Created Apr 1, 2021
leetcode-sort
View 280. Wiggle Sort.py
 class Solution: """ [3,5,2,1,6,4] n = 6 mid = 3 [1,2,3,5,6,4] i j i = mid-1 if n%2==0 tmp_arr = [3,4,2,6,1,5] 在把tmp_arr猜回array
Created Mar 21, 2021
leetcode-dp
View 53. Maximum Subarray.py
 class Solution: def maxSubArray(self, nums: List[int]) -> int: def get_cross_sum(nums, left, right, mid): left_subsum = float("-inf") cross_sum = 0 for i in range(mid, left-1, -1): cross_sum += nums[i] left_subsum = max(left_subsum, cross_sum) left_subsum = left_subsum if left_subsum != float("-inf") else 0
Created Mar 19, 2021
leetcode-dp
View 5. Longest Palindromic Substring.py
 class Solution: """ PC: there might be multiple valid answer <---i s = "babad" i j i從後面遍歷到前面, j從i遍歷到後面
Created Mar 19, 2021
leetcode-union-find
View 128. Longest Consecutive Sequence.py
 class UnionFind: def __init__(self, n): self._parents = [node for node in range(n)] self._rank = [1 for _ in range(n)] def find(self, u): while u != self._parents[u]: self._parents[u] = self._parents[self._parents[u]] u = self._parents[u] return u
Last active Mar 16, 2021
leetcode-array
View 153. Find Minimum in Rotated Sorted Array.py
 class Solution: def findMin(self, nums: List[int]) -> int: def find_pivot_element(nums, l, r): mid = l + (r-l) // 2 if r-l <= 1: return min(nums[l], nums[r]) if nums[l] < nums[r]: return nums[l] left_min = find_pivot_element(nums, l, mid-1)
Created Mar 13, 2021
leetcode-LL
View 445. Add Two Numbers II.py
 # Definition for singly-linked list. # class ListNode: # def __init__(self, val=0, next=None): # self.val = val # self.next = next class Solution: """ Solution: using stack -> O(n) in space we use stack to simulate addition.
Created Mar 13, 2021
leetcode-ll
View 1290. Convert Binary Number in a Linked List to Integer.py
 # Definition for singly-linked list. # class ListNode: # def __init__(self, val=0, next=None): # self.val = val # self.next = next class Solution: """ Naive Solution(如果你不懂binary representation) step1: reverse the linked list step2: travser the linked list and progressivly build the res
Created Mar 13, 2021
leetcode-LL
View 237. Delete Node in a Linked List.py
 # Definition for singly-linked list. # class ListNode: # def __init__(self, x): # self.val = x # self.next = None class Solution: """ PC: -we're not allowed to access head of linked list
Created Mar 13, 2021
leetcode-LL