Merge pull request AlgoStudyGroup#5 from MagicienDeCode/xl-kotlin-278-first-bad-version

jinshendan · web-flow · commit 429bd8db9806 · 2020-05-01T15:16:00.000+02:00
kotlin for leetcode 278 first bad version
diff --git a/May-LeetCoding-Challenge/First-Bad-Version/FirstBadVersionKotlin278.kt b/May-LeetCoding-Challenge/First-Bad-Version/FirstBadVersionKotlin278.kt
@@ -0,0 +1,21 @@
+class FirstBadVersionKotlin278 {
+    fun firstBadVersion(n: Int): Int {
+        var left = 0
+        var right = n
+        // never dead loop
+        while (left + 1 < right) {
+            val mid = left + (right - left) / 2
+            when {
+                // find first bad version, so move right to mid
+                isBadVersion(mid) -> right = mid
+                else -> left = mid
+            }
+        }
+        return when {
+            isBadVersion(left) -> left
+            else -> right
+        }
+    }
+
+    private fun isBadVersion(version: Int) = version > 3
+}
