feat: Revised the book (#978)

* Sync recent changes to the revised Word.

* Revised the preface chapter

* Revised the introduction chapter

* Revised the computation complexity chapter

* Revised the chapter data structure

* Revised the chapter array and linked list

* Revised the chapter stack and queue

* Revised the chapter hashing

* Revised the chapter tree

* Revised the chapter heap

* Revised the chapter graph

* Revised the chapter searching

* Reivised the sorting chapter

* Revised the divide and conquer chapter

* Revised the chapter backtacking

* Revised the DP chapter

* Revised the greedy chapter

* Revised the appendix chapter

* Revised the preface chapter doubly

* Revised the figures

codes/cpp/chapter_backtracking/n_queens.cpp

@@ -19,7 +19,7 @@ void backtrack(int row, int n, vector<vector<string>> &state, vector<vector<vect
         // 计算该格子对应的主对角线和副对角线
         int diag1 = row - col + n - 1;
         int diag2 = row + col;
-        // 剪枝：不允许该格子所在列、主对角线、副对角线存在皇后
+        // 剪枝：不允许该格子所在列、主对角线、副对角线上存在皇后
         if (!cols[col] && !diags1[diag1] && !diags2[diag2]) {
             // 尝试：将皇后放置在该格子
             state[row][col] = "Q";
@@ -38,8 +38,8 @@ vector<vector<vector<string>>> nQueens(int n) {
     // 初始化 n*n 大小的棋盘，其中 'Q' 代表皇后，'#' 代表空位
     vector<vector<string>> state(n, vector<string>(n, "#"));
     vector<bool> cols(n, false);           // 记录列是否有皇后
-    vector<bool> diags1(2 * n - 1, false); // 记录主对角线是否有皇后
-    vector<bool> diags2(2 * n - 1, false); // 记录副对角线是否有皇后
+    vector<bool> diags1(2 * n - 1, false); // 记录主对角线上是否有皇后
+    vector<bool> diags2(2 * n - 1, false); // 记录副对角线上是否有皇后
     vector<vector<vector<string>>> res;
 
     backtrack(0, n, state, res, cols, diags1, diags2);