Int overflow를 방지하는 스타일로 변경

Author: sonjh1217

find-minimum-in-rotated-sorted-array/sonjh1217.swift

@@ -4,7 +4,7 @@ class Solution {
         var high = nums.count - 1
 
         while low <= high {
-            let mid = (low + high) / 2
+            let mid = low + (high - low) / 2
 
             if nums[mid] < nums[mid - 1] {
                 return nums[mid]