May Challenge Day 1 done

problems/278/main.py

+# The isBadVersion API is already defined for you.
+# @param version, an integer
+# @return a bool
+# def isBadVersion(version):
+
+# I am assuming that the latest definitely is bad based on the way the problem is worded
+# so I will just implement a binary search pretty mcuh
+
+def isBadVersion(n):
+    return n >= 4
+
+class Solution:
+    def firstBadVersion(self, n):
+        # This check cuts out a case quickly, and also makes the logic easier to write
+        # because negatives and zeros no longer have to be dealt with
+        if isBadVersion(0):
+            return 0
+        knownGood = 0
+        knownBad = n
+        while knownBad - knownGood > 1:
+            # find the mid point
+            # check whether it's good or bad, and update accordingly
+            mid = (knownGood + knownBad) // 2
+            if isBadVersion(mid):
+                knownBad = mid
+            else:
+                knownGood = mid
+        return knownBad
+
+s = Solution()
+print("Expected: 4")
+print("Got:", s.firstBadVersion(5))

problems/278/problem.txt

+You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each version is developed based on the previous version, all the versions after a bad version are also bad.
+
+Suppose you have n versions [1, 2, ..., n] and you want to find out the first bad one, which causes all the following ones to be bad.
+
+You are given an API bool isBadVersion(version) which will return whether version is bad. Implement a function to find the first bad version. You should minimize the number of calls to the API.
+
+Example:
+
+Given n = 5, and version = 4 is the first bad version.
+
+call isBadVersion(3) -> false
+call isBadVersion(5) -> true
+call isBadVersion(4) -> true
+
+Then 4 is the first bad version. 
+

problems/278/run.sh

+#!/bin/bash
+
+python3 main.py