##### ###### ##### ### # # ### # # ###### ## ## ## ## ## ## ## # # # # # ## ##### #### ##### # # # # # # # #### ## # ## ## ## ## # # # # # ## ## # ###### ## ### # ### # ######
##### ###### ##### ### # # ### # # ###### ## ## ## ## ## ## ## # # # # # ## ##### #### ##### # # # # # # # #### ## # ## ## ## ## # # # # # ## ## # ###### ## ### # ### # ######
LeetCode 268
Given an array containing distinct numbers in the range , return the only number in the range that is missing from the array.
For example, if , then and the missing number is .
Hint: use the sum formula . The missing number equals the expected sum minus the actual sum.
