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krahets
2024-09-28 09:26:54 +08:00
parent 03a6cd27ca
commit 4ac4f94628
25 changed files with 119 additions and 162 deletions
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docs/chapter_backtracking/n_queens_problem.md
+4 -15
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@@ -532,11 +532,7 @@ comments: true
) {
// 当放置完所有行时，记录解
if row == n {
let mut copy_state: Vec<Vec<String>> = Vec::new();
for s_row in state.clone() {
copy_state.push(s_row);
}
res.push(copy_state);
res.push(state.clone());
return;
}
// 遍历所有列
@@ -547,12 +543,12 @@ comments: true
// 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.get_mut(row).unwrap()[col] = "Q".into();
state[row][col] = "Q".into();
(cols[col], diags1[diag1], diags2[diag2]) = (true, true, true);
// 放置下一行
backtrack(row + 1, n, state, res, cols, diags1, diags2);
// 回退：将该格子恢复为空位
state.get_mut(row).unwrap()[col] = "#".into();
state[row][col] = "#".into();
(cols[col], diags1[diag1], diags2[diag2]) = (false, false, false);
}
}
@@ -561,14 +557,7 @@ comments: true
/* 求解 n 皇后 */
fn n_queens(n: usize) -> Vec<Vec<Vec<String>>> {
// 初始化 n*n 大小的棋盘，其中 'Q' 代表皇后，'#' 代表空位
let mut state: Vec<Vec<String>> = Vec::new();
for _ in 0..n {
let mut row: Vec<String> = Vec::new();
for _ in 0..n {
row.push("#".into());
}
state.push(row);
}
let mut state: Vec<Vec<String>> = vec![vec!["#".to_string(); n]; n];
let mut cols = vec![false; n]; // 记录列是否有皇后
let mut diags1 = vec![false; 2 * n - 1]; // 记录主对角线上是否有皇后
let mut diags2 = vec![false; 2 * n - 1]; // 记录次对角线上是否有皇后