Finish problem 0278-first-bad-version

problems/0278-first-bad-version/solution.py

@@ -0,0 +1,14 @@
+def isBadVersion(version: int) -> bool:
+    raise NotImplementedError
+
+
+class Solution:
+    def firstBadVersion(self, n: int) -> int:
+        lo, hi = 1, n
+        while lo < hi:
+            check = (hi + lo) // 2
+            if isBadVersion(check):
+                hi = check
+            else:
+                lo = check + 1
+        return lo