diff --git a/433-240602-pass/main.py b/433-240602-pass/main.py
new file mode 100644
index 0000000..4df4041
--- /dev/null
+++ b/433-240602-pass/main.py
@@ -0,0 +1,38 @@
+class Solution:
+    def minMutation(self, startGene: str, endGene: str, bank: list[str]) -> int:
+        if endGene not in bank: return -1
+        que = []
+        front = -1
+        tail = -1
+        def push_back(que, front, tail, ele):
+            tail += 1
+            if tail >= len(que):
+                que.append(ele)
+            else:
+                que[tail] = ele
+            return tail
+        def pop(que, front ,tail):
+            front += 1
+            return (front , que[front])
+        tail = push_back(que,front,tail,(startGene,0))
+        def diff(str1, str2) -> int:
+            rlt = 0
+            for idx, ch in enumerate(str1):
+                if(str1[idx] != str2[idx]): rlt += 1
+            return rlt
+        rlt = 1e5
+        while front != tail:
+            (front, top_ele) = pop(que, front, tail)            
+            step = top_ele[1]
+            string = top_ele[0]
+            if diff(string, endGene) == 0: return step
+            for s in bank:
+                diff_num = diff(s, string)
+                # print(diff_num)
+                if diff_num == 1:
+                    tail = push_back(que, front, tail, (s, step + 1))
+        return -1
+
+sol = Solution()
+print(sol.minMutation("AACCGGTT","AACCGGTA",["AACCGGTA"]))
+print(sol.minMutation("AACCGGTT","AAACGGTA",["AACCGGTA","AACCGCTA","AAACGGTA"]))
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