Update the book based on the revised second edition (#1014)

* Revised the book

* Update the book with the second revised edition

* Revise base on the manuscript of the first edition

codes/python/chapter_backtracking/n_queens.py

@@ -21,10 +21,10 @@ def backtrack(
         return
     # 遍历所有列
     for col in range(n):
-        # 计算该格子对应的主对角线和副对角线
+        # 计算该格子对应的主对角线和次对角线
         diag1 = row - col + n - 1
         diag2 = row + col
-        # 剪枝：不允许该格子所在列、主对角线、副对角线上存在皇后
+        # 剪枝：不允许该格子所在列、主对角线、次对角线上存在皇后
         if not cols[col] and not diags1[diag1] and not diags2[diag2]:
             # 尝试：将皇后放置在该格子
             state[row][col] = "Q"
@@ -42,7 +42,7 @@ def n_queens(n: int) -> list[list[list[str]]]:
     state = [["#" for _ in range(n)] for _ in range(n)]
     cols = [False] * n  # 记录列是否有皇后
     diags1 = [False] * (2 * n - 1)  # 记录主对角线上是否有皇后
-    diags2 = [False] * (2 * n - 1)  # 记录副对角线上是否有皇后
+    diags2 = [False] * (2 * n - 1)  # 记录次对角线上是否有皇后
     res = []
     backtrack(0, n, state, res, cols, diags1, diags2)