"Algorithm"--1 to N to reduce a number, order is scrambled to find the missing number

Problem

There are 0-n this n+1 number, but one lost a number, how can I find out which number lost?

Five different methods

1) Subtract the sum of the current input data with 1+2+...+n. Time complexity: O (N) spatial complexity: O (1) "Easy Overflow"

2) Divide the total product of the current input data by 12... *n. Time complexity: O (N) spatial complexity: O (1) "Easy Overflow"

3) Use 1^2^...^n results to input data individually or at the current date. Complexity of Time: O (n) spatial complexity: O (1)

4) sort the input data and iterate through it from beginning to end. Time complexity O (nlogn) space complexity O (1)

5) hash The input data and iterate through it from beginning to end. Time complexity O (n) spatial complexity O (n)

"Algorithm"--1 to N to reduce a number, order is scrambled to find the missing number