用python编写递归算法,定义一个函数,只提供num_of_row一个参数,要求输出num_of_row行的杨辉三角,输出到Triangle.txt中,不需要返回值。并且Triangle.txt保存在我的桌面上
时间: 2024-05-06 19:19:17 浏览: 84
好的,这是一个技术问题,我可以回答。以下是Python编写递归算法,定义一个函数,只提供num_of_row一个参数,要求输出num_of_row行的杨辉三角,并输出到Triangle.txt中的代码:
```
def generate_triangle(row, col):
if col == 0 or row == col:
return 1
return generate_triangle(row - 1, col - 1) + generate_triangle(row - 1, col)
def generate_yanghui_triangle(num_of_row):
with open('/Users/your_username/Desktop/Triangle.txt', 'w') as f:
for i in range(num_of_row):
row_string = ''
for j in range(i+1):
row_string += str(generate_triangle(i, j)) + ' '
row_string += '\n'
f.write(row_string)
```
你可以将`/Users/your_username/Desktop`替换为你自己的桌面路径。
相关问题
python用递归函数解九宫格数独
可以使用递归函数和回溯算法来解决九宫格数独问题。以下是一个简单的 Python 代码示例:
```python
def solve(board):
"""
Solve the Sudoku puzzle using recursive backtracking.
:param board: 2D list of integers representing the Sudoku puzzle
:return: boolean indicating if the puzzle is solved
"""
empty_cell = find_empty(board)
if not empty_cell:
return True
row, col = empty_cell
for num in range(1, 10):
if is_valid(board, row, col, num):
board[row][col] = num
if solve(board):
return True
board[row][col] = 0
return False
def find_empty(board):
"""
Find an empty cell in the Sudoku puzzle.
:param board: 2D list of integers representing the Sudoku puzzle
:return: tuple containing the row and column of an empty cell, or None if there are no empty cells
"""
for row in range(9):
for col in range(9):
if board[row][col] == 0:
return (row, col)
return None
def is_valid(board, row, col, num):
"""
Check if a number can be placed in a given cell in the Sudoku puzzle.
:param board: 2D list of integers representing the Sudoku puzzle
:param row: integer representing the row of the cell to check
:param col: integer representing the column of the cell to check
:param num: integer representing the number to check
:return: boolean indicating if the number can be placed in the cell
"""
# Check row
for i in range(9):
if board[row][i] == num:
return False
# Check column
for i in range(9):
if board[i][col] == num:
return False
# Check square
square_row = (row // 3) * 3
square_col = (col // 3) * 3
for i in range(square_row, square_row + 3):
for j in range(square_col, square_col + 3):
if board[i][j] == num:
return False
return True
```
使用该函数,您可以通过以下方式调用它:
```python
board = [
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0]
]
solve(board)
for row in board:
print(row)
```
该代码将打印已解决数独的完整板。
用python编写一个 BFS 算法和一个 DFS 算 法来求解八数码问题并添加注释
当然可以,这里我会为你展示如何用 Python 编写广度优先搜索(BFS)和深度优先搜索(DFS)算法来解决经典的八数码问题(又称数独)。我们首先假设已经有一个函数 `check_sudoku` 来检查给定的数组是否满足数独规则。
```python
import collections
# 定义数独的空格
def empty_board():
return [[0] * 9 for _ in range(9)]
# 检查给定的数独布局是否有效
def check_sudoku(board):
# 逻辑省略,你可以自行实现九宫格划分、行、列和宫的遍历以及数字重复性的检查
pass
# 广度优先搜索(BFS)
def bfs_solve(board):
visited = set()
queue = collections.deque([[i // 9, i % 9, board.copy()] for i in range(81) if board[i] == 0]) # 初始化队列
while queue:
row, col, current_board = queue.popleft() # 弹出队首元素
if (row, col) not in visited:
visited.add((row, col))
for num in range(1, 10): # 尝试填入数字
if is_valid_move(row, col, num, current_board):
current_board[row][col] = num
if check_sudoku(current_board):
return current_board # 找到解决方案,返回
else:
queue.append([row, col, current_board]) # 无效则回溯
return None # 没有找到解决方案
# 深度优先搜索(DFS)
def dfs_solve(board):
def backtrack(row, col):
nonlocal found_solution
if row == 9:
found_solution = True
return
for num in range(1, 10):
if is_valid_move(row, col, num, board):
board[row][col] = num
if check_sudoku(board):
solution.append(board.copy())
found_solution = True
else:
backtrack(row + 1, col) # 递归尝试下一个位置
board[row][col] = 0 # 回溯,撤销当前选择
found_solution = False
solution = []
backtrack(0, 0)
return solution if found_solution else None # 返回所有解决方案列表
# 判断当前位置填入num是否合法
def is_valid_move(row, col, num, board):
# 省略对行、列和宫的检查逻辑
pass
# 示例用法
board = empty_board()
solution_bfs = bfs_solve(board)
solution_dfs = dfs_solve(board)
if solution_bfs:
print("BFS Solution:")
print(solution_bfs)
else:
print("BFS couldn't find a solution.")
if solution_dfs:
print("\nDFS Solutions:")
for sol in solution_dfs:
print(sol)
else:
print("DFS couldn't find a solution.")
```
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