Add solution for N-Queens II

camp1/week3/leetcode/n-queens-ii.py

@@ -0,0 +1,25 @@
+class Solution:
+    def totalNQueens(self, n: int) -> int:
+        posDiag=set()
+        negDiag=set()
+
+        count=0
+
+        def backtrack(row,columns):
+            nonlocal count
+            if row==n:
+                count+=1
+                return
+            for col in range(n):
+                if col in columns or (row+col) in posDiag or (row-col) in negDiag:
+                    continue
+                columns.append(col)
+                posDiag.add(col+row)
+                negDiag.add(row-col)
+                backtrack(row+1,columns)
+                columns.pop()
+                posDiag.remove(col+row)
+                negDiag.remove(row-col)
+        backtrack(0,[])
+
+        return count