回溯 递归 的回退状态
func solveSudoku(board [][]byte) {
var line, column [9][9]bool
var block [3][3][9]bool
var spaces [][2]int
for i, row := range board {
for j, b := range row {
if b == '.' {
spaces = append(spaces, [2]int{i, j})
} else {
digit := b - '1'
line[i][digit] = true
column[j][digit] = true
block[i/3][j/3][digit] = true
}
}
}
var dfs func(int) bool
dfs = func(pos int) bool {
if pos == len(spaces) {
return true
}
i, j := spaces[pos][0], spaces[pos][1]
for digit := byte(0); digit < 9; digit++ {
if !line[i][digit] && !column[j][digit] && !block[i/3][j/3][digit] {
line[i][digit] = true
column[j][digit] = true
block[i/3][j/3][digit] = true
board[i][j] = digit + '1'
if dfs(pos + 1) {
return true
}
line[i][digit] = false
column[j][digit] = false
block[i/3][j/3][digit] = false
}
}
return false
}
dfs(0)
}
/*
ASCII（American Standard Code for Information Interchange，美国信息交换标准代码）
. 46
/ 47
0 48
9 57
*/
/*
37. 解数独 - 力扣（LeetCode） https://leetcode.cn/problems/sudoku-solver/
解数独 - 解数独 - 力扣（LeetCode） https://leetcode.cn/problems/sudoku-solver/solution/jie-shu-du-by-leetcode-solution/
*/
