以下leetcode问题中的运行时错误

Question

问题 link - https://leetcode.com/problems/maximum-average-subarray-i/

class Solution 
{
public:
double findMaxAverage(vector<int>& nums, int k)
{
deque<pair<int,int>> d;       //deque since its a sliding window problem
vector<double> ans;          //to return answer
double avg;
double sum=0;
int n=nums.size();

        for(int i=0;i<n;i++)
        {
            if(!d.empty() && d.front().second<=(i-k))                 //out of window size
            {
                avg=sum/k;
                ans.push_back(avg);          //push the average of k elements in answer vector
                sum=sum-d.front().first;     //remove the sum of first element when moving to next
                d.pop_front();               //remove front element of deque
                
            }
            
            d.push_back(make_pair(nums[i],i)); //push current element in deque
            sum=sum+d.back().first;            //add it to sum
            
        }
        
        return *max_element(ans.begin(), ans.end());   //return maximum average of subarray
    }
};

我试图解决 leetcode 问题 643 最大平均子数组 I ，这是一个基于滑动 window 方法的简单问题。

我写了代码并得到了运行时错误提示 “第 811 行：字符 16：运行时错误：引用绑定到 'double' 类型的空指针 (stl_iterator.h) 摘要：UndefinedBehaviorSanitizer：未定义行为 /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c"

有人可以帮忙吗？提前致谢。

Answer 1

错误在这里

return *max_element(ans.begin(), ans.end());

如果 ans 为空，则取消引用 ans.end()。

以下leetcode问题中的运行时错误

Runtime error in following leetcode problem

c++

algorithm

data-structures

sliding-window