Create 0052-n-queens-ii.kt

Author: a93a

kotlin/0052-n-queens-ii.kt

@@ -0,0 +1,34 @@
+class Solution {
+    fun totalNQueens(n: Int): Int {
+
+        val cols = HashSet<Int>()
+        val pD = HashSet<Int>()
+        val nD = HashSet<Int>()
+        var res = 0
+
+        fun fill(row: Int) {    
+
+            if(row == n) {
+                res++
+                return
+            }
+
+            for(col in 0 until n) {
+                if(cols.contains(col) || pD.contains(row + col) || nD.contains(row - col)) continue
+
+                cols.add(col)
+                pD.add(row + col)
+                nD.add(row - col)
+
+                fill(row+1)
+
+                cols.remove(col)
+                pD.remove(row + col)
+                nD.remove(row - col)
+            }
+        }
+
+        fill(0)
+        return res
+    }
+}