I have the following function

    void rotate(vector<int>& nums, int k) {
        int original_size = nums.size();
        k = k%original_size;
        nums.insert(nums.begin(), nums.end()-k, nums.end());
        nums.resize(original_size);
    }

For these inputs, I get the proper result

[1,2,3,4,5,6,7]
3
----
[5,6,7,1,2,3,4]

============
[-1]
2
----
[-1]

However, for the input below, I am getting the wrong result.

[1,2,3]
1
----
[2,1,2]

It seems that the nums.insert(nums.begin(), nums.end()-k, nums.end()); properly works on the first two example, but not on the third one. I can't think of why is that.

CodePudding user response：

You may not use insert with first and last being iterators to the same vector. That is because inserting elements invalidates iterators. From cppreference (overload 4):

The behavior is undefined if first and last are iterators into *this.

You can use std::rotate to rotate elements in a vector.