added python solution for 0052-n-queens-ii

Author: leej1230

python/0052-n-queens-ii.py

@@ -0,0 +1,30 @@
+class Solution:
+    def totalNQueens(self, n: int) -> int:
+        answer = 0
+
+        cols = set()
+        posdiag = set()
+        negdiag = set()
+
+        def backtrack(i):
+            if i == n:
+                nonlocal answer
+                answer += 1
+                return
+            
+            for j in range(n):
+                if j in cols or (i+j) in posdiag or (i-j) in negdiag:
+                    continue
+
+                cols.add(j)
+                posdiag.add(i+j)
+                negdiag.add(i-j)
+
+                backtrack(i+1)
+                
+                cols.remove(j)
+                posdiag.remove(i+j)
+                negdiag.remove(i-j)
+        
+        backtrack(0)
+        return answer