algorithm/hello-algo
1
0
Fork 0
mirror of https://github.com/krahets/hello-algo.git synced 2025-11-02 12:58:42 +08:00
Code Issues Packages Projects Releases Wiki Activity

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

Browse Source 
* 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
Download Patch File Download Diff File Expand all files Collapse all files

6
codes/swift/chapter_backtracking/n_queens.swift
View File

@ -13,10 +13,10 @@ func backtrack(row: Int, n: Int, state: inout [[String]], res: inout [[[String]]
}
// 遍历所有列
for col in 0 ..< 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
let diag1 = row - col + n - 1
let 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"
@ -40,7 +40,7 @@ func nQueens(n: Int) -> [[[String]]] {
var state = Array(repeating: Array(repeating: "#", count: n), count: n)
var cols = Array(repeating: false, count: n) // 记录列是否有皇后
var diags1 = Array(repeating: false, count: 2 * n - 1) // 记录主对角线上是否有皇后
var diags2 = Array(repeating: false, count: 2 * n - 1) // 记录副对角线上是否有皇后
var diags2 = Array(repeating: false, count: 2 * n - 1) // 记录次对角线上是否有皇后
var res: [[[String]]] = []
backtrack(row: 0, n: n, state: &state, res: &res, cols: &cols, diags1: &diags1, diags2: &diags2)