Add solution for HumanEval11 (#177)

Author: TwoFX

HumanEvalLean/HumanEval11.lean

@@ -1,5 +1,17 @@
-def string_xor : Unit :=
-  ()
+import Std.Data.Iterators
+
+def stringXor (a b : List Bool) : List Bool :=
+  ((a.iter).zip b.iter)
+    |>.map (fun p => Bool.xor p.1 p.2)
+    |>.toList
+
+@[simp, grind]
+theorem length_stringXor {a b : List Bool} : (stringXor a b).length = min a.length b.length := by
+  simp [stringXor]
+
+theorem getElem_stringXor {a b : List Bool} {i : Nat} {hia : i < a.length} {hib : i < b.length} :
+    (stringXor a b)[i]'(by grind) = Bool.xor a[i] b[i] := by
+  simp [stringXor]
 
 /-!
 ## Prompt
@@ -44,4 +56,4 @@ def check(candidate):
     assert candidate('1', '1') == '0'
     assert candidate('0101', '0000') == '0101'
 ```
--/
+-/

lean-toolchain

@@ -1 +1 @@
-leanprover/lean4:nightly-2025-08-18
+leanprover/lean4:nightly-2025-06-11