"Leetcode" 136.Excel Sheet Column Title

Given an array of integers, every element appears twice except for one. Find the single one.

Note:
Your algorithm should has a linear runtime complexity. Could you implement it without using extra memory?

Hide TagsHash Table Bit manipulationThe title requirement is a specific condition, and only one numeric value appears once

1 classSolution {2  Public:3     intSinglenumber (intA[],intN) {4         intx;5          for(size_t i=0; i<n; ++i)6X ^=A[i];7         returnx;8     }9};

Status:AcceptedRuntime:18 mssubmitted:3 months, 3 weeks ago but I think the x here is not initialized, find C++primer version fifth, P40 page has the corresponding default initialization definition: "If a variable of a built-in type is not being displayed initialized, Its value is determined by the location of the definition. Variables defined outside of any function body are initialized to 0. Built-in type variables defined inside the function body will not be initialized. "The main function is also a function, so the global variable is initialized to 0, is the member function in the class initialized to 0?" This is not yet confirmed. So I changed the next

1 intSinglenumber (intA[],intN) {2     if(N <1)3         returnNULL;4     intx = a[0];5      for(size_t i=1; i<n; ++i)6X ^=A[i];7     returnx;8}

At this time unexpectedly does not have AC, prompt compile Error

Line 19:no matching function for call to ' Solution::singlenumber (std::vector<int>&) '

"Leetcode" 136.Excel Sheet Column Title