给定一个大小为N的数组arr[] ，使用 Stack 反转数组的任务。
例子：
Input: arr[] = { 10, 20, 30, 40, 50 }
Output: 50 40 30 20 10
Explanation:
Reversing the array modifies arr[] to { 50, 40, 30, 20, 10 }
Therefore, the required output is 50 40 30 20 10.
Input: arr[] = { 1 }
Output: 1
Iterative and Recursive Approach：参考文章reverse an array，以迭代或递归的方式解决这个问题。
时间复杂度： O(N)
辅助空间： O(1)
基于堆栈的方法：按照以下步骤解决问题：
- 初始化一个 Stack 来存储数组元素。
- 遍历数组并将所有数组元素压入栈中。
- > 从堆栈中弹出元素并插入到数组中。
- 最后，打印数组。
下面是上述方法的实现：
C++
// C++ program to implement // the above approach #includeusing namespace std; // Structure of stack class Stack { public: // Stores index of top // element of a stack int top; // Stores maximum count of // elements stored in a stack unsigned capacity; // Stores address of // array element int* array; }; // Function to Initialize a stack // of given capacity. Stack* createStack(unsigned capacity) { Stack* stack = new Stack(); stack->capacity = capacity; stack->top = -1; stack->array = new int[(stack->capacity * sizeof(int))]; return stack; } // Function to check if // the stack is full or not int isFull(Stack* stack) { return stack->top == stack->capacity - 1; } // Function to check if // the stack is empty or not int isEmpty(Stack* stack) { return stack->top == -1; } // Function to insert an element // into the stack. void push(Stack* stack, int item) { // If stack is full if (isFull(stack)) return; // Insert element into stack stack->array[++stack->top] = item; } // Function to remove an element // from stack. int pop(Stack* stack) { // If stack is empty if (isEmpty(stack)) return -1; // Pop element from stack return stack->array[stack->top--]; } // Function to reverse the array elements void reverseArray(int arr[], int n) { // Initialize a stack of capacity n Stack* stack = createStack(n); for (int i = 0; i < n; i++) { // Insert arr[i] into the stack push(stack, arr[i]); } // Reverse the array elements for (int i = 0; i < n; i++) { // Update arr[i] arr[i] = pop(stack); } // Print array elements for (int i = 0; i < n; i++) cout << arr[i] << " "; } // Driver Code int main() { int arr[] = { 100, 200, 300, 400 }; int N = sizeof(arr) / sizeof(arr[0]); reverseArray(arr, N); return 0; }
C
// C program to implement // the above approach #include#include #include #include // Structure of stack struct Stack { // Stores index of top // element of a stack int top; // Stores maximum count of // elements stored in a stack unsigned capacity; // Stores address of // array element int* array; }; // Function to Initialize a stack // of given capacity. struct Stack* createStack(unsigned capacity) { struct Stack* stack = (struct Stack*)malloc( sizeof(struct Stack)); stack->capacity = capacity; stack->top = -1; stack->array = (int*)malloc( stack->capacity * sizeof(int)); return stack; } // Function to check if // the stack is full or not int isFull(struct Stack* stack) { return stack->top == stack->capacity - 1; } // Function to check if // the stack is empty or not int isEmpty(struct Stack* stack) { return stack->top == -1; } // Function to insert an element // into the stack. void push(struct Stack* stack, int item) { // If stack is full if (isFull(stack)) return; // Insert element into stack stack->array[++stack->top] = item; } // Function to remove an element // from stack. int pop(struct Stack* stack) { // If stack is empty if (isEmpty(stack)) return -1; // Pop element from stack return stack->array[stack->top--]; } // Function to reverse the array elements void reverseArray(int arr[], int n) { // Initialize a stack of capacity n struct Stack* stack = createStack(n); for (int i = 0; i < n; i++) { // Insert arr[i] into the stack push(stack, arr[i]); } // Reverse the array elements for (int i = 0; i < n; i++) { // Update arr[i] arr[i] = pop(stack); } // Print array elements for (int i = 0; i < n; i++) printf("%d ", arr[i]); } // Driver Code int main() { int arr[] = { 100, 200, 300, 400 }; int N = sizeof(arr) / sizeof(arr[0]); reverseArray(arr, N); return 0; }
Java
// Java program to implement // the above approach import java.util.*; // Structure of stack class Stack { // Stores maximum count of // elements stored in a stack int size; // Stores index of top // element of a stack int top; // Stores address of // array element int[] a; // Function to check if // the stack is empty or not boolean isEmpty() { return (top < 0); } // Function to Initialize // a stack of given capacity. Stack(int n) { top = -1; size = n; a = new int[size]; } // Function to push // an element into Stack boolean push(int x) { // If Stack is full if (top >= size) { System.out.println( "Stack Overflow"); return false; } else { // Insert element // into stack a[++top] = x; return true; } } // Function to remove an element // from stack. int pop() { // If stack is empty if (top < 0) { System.out.println( "Stack Underflow"); return 0; } // Pop element from stack else { int x = a[top--]; return x; } } } // Driver Code class Main { // Function to reverse the array elements public static void reverse(int arr[], int n) { // Initialize a stack of capacity n Stack obj = new Stack(n); for (int i = 0; i < n; i++) { // Insert arr[i] into the stack obj.push(arr[i]); } // Reverse the array elements for (int i = 0; i < n; i++) { // Update arr[i] arr[i] = obj.pop(); } // Print array elements for (int i = 0; i < n; i++) { System.out.print(arr[i] + " "); } } // Driver function public static void main(String args[]) { int n = 4; // Create a new array int[] a = new int[] { 100, 200, 300, 400 }; // Call reverse method reverse(a, n); } }
输出：400 300 200 100时间复杂度： O(N)
辅助空间： O(N) 。如果您想与行业专家一起参加直播课程，请参阅Geeks Classes Live