T1 LC202 快乐数

  1. class Solution:
  2.     def isHappy(self, n: int) -> bool:
  3.         left=sum([int(i)*int(i) for i in str(n)])
  4.         right=sum([int(i)*int(i) for i in str(left)])
  5.         if left==1 or right==1:return True
  7.         while left!=right:
  8.             left=sum([int(i)*int(i) for i in str(left)])
  9.             right=sum([int(i)*int(i) for i in str(right)])
  10.             right=sum([int(i)*int(i) for i in str(right)])
  11.             if right==1 or left==1:
  12.                 return True
  13.         return False

T2 LC92 反转列表

  1. class Solution:
  2.     def reverseBetween(self, head: ListNode, m: int, n: int) -> ListNode:
  3.         # m对应节点是头结点，直接翻转
  4.         if m == 1: return self.reverse(head, m, n)
  6.         count = 1
  7.         h = head
  8.         while h:    #找到m前一个节点preRev
  9.             if count == m - 1:
  10.                 preRev = h 
  11.             h = h.next
  12.             count += 1
  13.         headRev = self.reverse(preRev.next, m, n)
  14.         preRev.next = headRev 
  15.         return head
  17.     def reverse(self, head, m, n):
  18.         '''
  19.         该函数完成m-n的翻转以及翻转后与剩余链表相连两个任务
  20.         '''
  21.         pre, cur = None, head
  22.         #翻转m-n链表
  23.         for _ in range(n - m + 1):
  24.             pre, pre.next, cur = cur, pre, cur.next
  25.         head.next = cur #与剩余链表相连
  26.         return pre

T3 LC51 N皇后

  1. class Solution:
  2.     def solveNQueens(self, n: int) -> List[List[str]]:
  3.         def could_place(row, col):
  4.             return not (cols[col] + hill_diagonals[row - col] + dale_diagonals[row + col])
  6.         def place_queen(row, col):
  7.             queens.add((row, col))
  8.             cols[col] = 1
  9.             hill_diagonals[row - col] = 1
  10.             dale_diagonals[row + col] = 1
  12.         def remove_queen(row, col):
  13.             queens.remove((row, col))
  14.             cols[col] = 0
  15.             hill_diagonals[row - col] = 0
  16.             dale_diagonals[row + col] = 0
  18.         def add_solution():
  19.             solution = []
  20.             for _, col in sorted(queens):
  21.                 solution.append('.' * col + 'Q' + '.' * (n - col - 1))
  22.             output.append(solution)
  24.         def backtrack(row = 0):
  25.             for col in range(n):
  26.                 if could_place(row, col):
  27.                     place_queen(row, col)
  28.                     if row + 1 == n:
  29.                         add_solution()
  30.                     else:
  31.                         backtrack(row + 1)
  32.                     remove_queen(row, col)
  34.         cols = [0] * n
  35.         hill_diagonals = [0] * (2 * n - 1)
  36.         dale_diagonals = [0] * (2 * n - 1)
  37.         queens = set()
  38.         output = []
  39.         backtrack()
  40.         return output

今日学习总结

提交了学校CPP OJ的作业