N Queens golang

go/51-N-Queens.go

@@ -0,0 +1,32 @@
+package main
+
+func solveNQueens(n int) [][]string {
+ ans, curr := make([][]string, 0), make([]string, 0)
+ column, diag1, diag2 := make(map[int]int), make(map[int]int), make(map[int]int)
+ var backtrack func(y int)
+ backtrack = func(y int) {
+ if y == n {
+ ans = append(ans, append([]string{}, curr...))
+ }
+ for x := 0; x < n; x++ {
+ if column[x] > 0 || diag1[x+y] > 0 || diag2[n+x-y-1] > 0 {
+ continue
+ }
+ column[x], diag1[x+y], diag2[n+x-y-1] = 1, 1, 1
+ s := ""
+ for i := 0; i < n; i++ {
+ if i == x {
+ s += "Q"
+ } else {
+ s += "."
+ }
+ }
+ curr = append(curr, s)
+ backtrack(y + 1)
+ column[x], diag1[x+y], diag2[n+x-y-1] = 0, 0, 0
+ curr = curr[:len(curr)-1]
+ }
+ }
+ backtrack(0)
+ return ans
+}