Given an array of ints length 3, return an array with the elements "rotated left" so {1, 2, 3} yields {2, 3, 1}.
时间: 2024-02-02 07:04:49 浏览: 28
以下是 Python 代码实现:
```python
def rotate_left3(nums):
return [nums[1], nums[2], nums[0]]
```
这个函数接受一个长度为 3 的整数数组 `nums` 作为输入,返回一个新的数组,其中元素“向左旋转了一次”,即原来的第一个元素成为新数组的最后一个元素,原来的第二个元素成为新数组的第一个元素,原来的第三个元素成为新数组的第二个元素。
例如,`rotate_left3([1, 2, 3])` 的返回值为 `[2, 3, 1]`。
相关问题
Eigen::Vector3d v_rotated = rotation_vector * v;
这段代码将旋转向量rotation_vector作用于向量v上,得到旋转后的向量v_rotated。在Eigen库中,向量与矩阵的乘法采用的是矩阵乘法规则,即左乘旋转矩阵或者右乘变换矩阵。在这里,我们采用的是左乘旋转矩阵的方式,即先将旋转向量通过指数映射(exp)转换成旋转矩阵(rotation matrix),然后将旋转矩阵与原始向量v相乘,得到旋转后的向量v_rotated。因此,v_rotated的值为旋转后的结果,其类型为Eigen::Vector3d。
write a C++ program for constructing a heap (max heap) with integers and printing it in the rotated form.
Here is a C++ program that constructs a max heap with integers and prints it in the rotated form:
```cpp
#include <iostream>
#include <vector>
using namespace std;
// function to swap two integers
void swap(int& a, int& b)
{
int temp = a;
a = b;
b = temp;
}
// function to heapify the given vector
void heapify(vector<int>& arr, int n, int i)
{
int largest = i; // initialize largest as root
int left = 2*i + 1; // left child index
int right = 2*i + 2; // right child index
// if left child is larger than root
if (left < n && arr[left] > arr[largest])
largest = left;
// if right child is larger than largest so far
if (right < n && arr[right] > arr[largest])
largest = right;
// if largest is not root
if (largest != i)
{
// swap the root with largest element
swap(arr[i], arr[largest]);
// recursively heapify the affected sub-tree
heapify(arr, n, largest);
}
}
// function to build max heap
void buildMaxHeap(vector<int>& arr, int n)
{
// start from the last non-leaf node and heapify each node
for (int i = n / 2 - 1; i >= 0; i--)
heapify(arr, n, i);
}
// function to print the heap in the rotated form
void printRotatedHeap(vector<int>& arr, int n)
{
int height = log2(n) + 1; // height of the heap
int index = 0; // current index in the heap
int spaces = pow(2, height - 1) - 1; // number of spaces before the first element of the current level
// print each level of the heap in the rotated form
for (int i = 0; i < height; i++)
{
// print the spaces before the first element of the current level
for (int j = 0; j < spaces; j++)
cout << " ";
// print the elements of the current level
for (int j = 0; j < pow(2, i) && index < n; j++)
{
cout << arr[index++] << " ";
// print the spaces between elements of the current level
for (int k = 0; k < 2 * spaces + 1; k++)
cout << " ";
}
// move to the next line and adjust the number of spaces for the next level
cout << endl;
spaces /= 2;
}
}
int main()
{
int n;
cout << "Enter the number of elements: ";
cin >> n;
vector<int> arr(n);
cout << "Enter the elements: ";
for (int i = 0; i < n; i++)
cin >> arr[i];
// build max heap
buildMaxHeap(arr, n);
// print the heap in the rotated form
cout << "Max heap in the rotated form:\n";
printRotatedHeap(arr, n);
return 0;
}
```
In this program, we first define a `swap` function to swap two integers, and a `heapify` function to heapify the sub-tree rooted at a given index `i` in the given vector `arr`. We then define a `buildMaxHeap` function to build the max heap from the given vector `arr`. Finally, we define a `printRotatedHeap` function to print the max heap in the rotated form.
In the `main` function, we first read the number of elements and the elements themselves from the user using `cin`. We then build the max heap using `buildMaxHeap` function, and print the heap in the rotated form using `printRotatedHeap` function.
The `printRotatedHeap` function uses the height of the heap to determine the number of levels, and the number of spaces before the first element of each level. It then prints each level of the heap in the rotated form, by printing the elements of the level followed by the spaces between elements.
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