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

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* Revised the book

* Update the book with the second revised edition

* Revise base on the manuscript of the first edition
This commit is contained in:
Yudong Jin
2023-12-28 18:06:09 +08:00
committed by GitHub
parent 19dde675df
commit f68bbb0d59
261 changed files with 643 additions and 647 deletions
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6
codes/dart/chapter_backtracking/n_queens.dart
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@ -25,10 +25,10 @@ void backtrack(
}
// 遍历所有列
for (int col = 0; col < n; col++) {
// 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
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 (!cols[col] && !diags1[diag1] && !diags2[diag2]) {
// 尝试：将皇后放置在该格子
state[row][col] = "Q";
@ -52,7 +52,7 @@ List<List<List<String>>> nQueens(int n) {
List<List<String>> state = List.generate(n, (index) => List.filled(n, "#"));
List<bool> cols = List.filled(n, false); // 记录列是否有皇后
List<bool> diags1 = List.filled(2 * n - 1, false); // 记录主对角线上是否有皇后
List<bool> diags2 = List.filled(2 * n - 1, false); // 记录副对角线上是否有皇后
List<bool> diags2 = List.filled(2 * n - 1, false); // 记录次对角线上是否有皇后
List<List<List<String>>> res = [];
backtrack(0, n, state, res, cols, diags1, diags2);