[LeetCode] Add January 30.

solved/LeetCode/Challenges/2020/January/30.kt

@@ -0,0 +1,30 @@
+class Solution {
+  fun minimumDeviation(nums: IntArray): Int {
+    val s = TreeSet<Int>()
+    for (i in nums) {
+      s.add(i)
+    }
+
+    var best = s.last() - s.first()
+
+    while (isOdd(s.first())) {
+      s.add(s.pollFirst() * 2)
+      best = Math.min(best, s.last() - s.first())
+    }
+
+    while (isEven(s.last())) {
+      s.add(s.pollLast() / 2)
+      best = Math.min(best, s.last() - s.first())
+    }
+
+    return best
+  }
+
+  private fun isEven(x: Int): Boolean {
+    return (x % 2) == 0
+  }
+
+  private fun isOdd(x: Int): Boolean {
+    return (x % 2) == 1
+  }
+}