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我尝试了这个用 Python 编写的数独解算器 https://freepythontips.wordpress.com/2013/09/01/sudoku-solver-in-python/ 代码运行良好。这是完整的代码:
import sys
def same_row(i,j): return (i/9 == j/9)
def same_col(i,j): return (i-j) % 9 == 0
def same_block(i,j): return (i/27 == j/27 and i%9/3 == j%9/3)
def r(a):
i = a.find('0')
if i == -1:
sys.exit(a)
excluded_numbers = set()
for j in range(81):
if same_row(i,j) or same_col(i,j) or same_block(i,j):
excluded_numbers.add(a[j])
for m in '123456789':
if m not in excluded_numbers:
r(a[:i]+m+a[i+1:])
r('100070030830600000002900608600004907090000050307500004203009100000002043040080009')
我不明白这个循环:
for m in '123456789':
if m not in excluded_numbers:
r(a[:i]+m+a[i+1:])
请有人解释这段代码的算法。谢谢
编辑: 我问的是那个循环的逻辑，现在我明白了逻辑，我检查了 Peter Novig 的数独解算器。