# 删除小于下一个或变得更小的数组元素 > 原文： [https://www.geeksforgeeks.org/delete-array-elements-which-are-smaller-than-next-or-become-smaller/](https://www.geeksforgeeks.org/delete-array-elements-which-are-smaller-than-next-or-become-smaller/) 给定一个数组`arr[]`和一个数字`k`。 任务是删除小于下一个元素的`k`个元素（即，如果`arr[i] < arr[i + 1]`则删除`arr[i]`）或由于下一个元素被删除而变得小于下一个元素。 例子： ``` Input : arr[] = { 3, 100, 1 } k = 1 Output : 100, 1 Explanation : arr[0] < arr[1] means 3 is less than 100, so delete 3 Input : arr[] = {20, 10, 25, 30, 40} k = 2 Output : 25 30 40 Explanation : First we delete 10 because it follows arr[i] < arr[i+1]. Then we delete 20 because 25 is moved next to it and it also starts following the condition. Input : arr[] = { 23, 45, 11, 77, 18} k = 3 Output : 77, 18 Explanation : We delete 23, 45 and 11 as they follow the condition arr[i] < arr[i+1] ``` **方法**： [堆栈](https://www.geeksforgeeks.org/stack-data-structure-introduction-program/)用于解决此问题。 首先，我们将`arr[0]`推入堆栈`S`，然后将`count`初始化为 0，然后从 1 遍历到`n`，然后检查`s.top() < arr[i]`是否为`true`，然后弹出堆栈中的元素，如果`count == k`，则增加计数，然后我们停止循环，然后将堆栈的值存储在另一个数组中，然后打印该数组。 ## C++ ```cpp // C++ program to delete elements from array. #include <bits/stdc++.h> using namespace std; // Function for deleting k elements void deleteElements(int arr[], int n, int k) {      // Create a stack and push arr[0]     stack<int> s;     s.push(arr[0]);     int count = 0;     // traversing a loop from i = 1 to n     for (int i=1; i<n; i++) {         // condition for deleting an element         while (!s.empty() && s.top() < arr[i]                              && count < k) {                                                  s.pop();             count++;         }         s.push(arr[i]);     }     // Putting elements of stack in a vector     // from end to begin.     int m = s.size();     vector<int> v(m); // Size of vector is m     while (!s.empty()) {         // push element from stack to vector v         v[--m] = s.top();         s.pop();     }     // printing result     for (auto x : v)         cout << x << " ";     cout << endl; } // Driver code int main() {     int n = 5, k = 2;     int arr[] = {20, 10, 25, 30, 40};      deleteElements(arr, n, k);     return 0; } ``` ## Java ```java import java.util.*; //Java program to delete elements from array. class GFG { // Function for deleting k elements     static void deleteElements(int arr[], int n, int k) {         // Create a stack and push arr[0]         Stack<Integer> s = new Stack<>();         s.push(arr[0]);         int count = 0;         // traversing a loop from i = 1 to n         for (int i = 1; i < n; i++) {             // condition for deleting an element             while (!s.empty() && s.peek() < arr[i]                     && count < k) {                 s.pop();                 count++;             }             s.push(arr[i]);         }         // Putting elements of stack in a vector         // from end to begin.         int m = s.size();         Integer[] v = new Integer[m]; // Size of vector is m         while (!s.empty()) {             // push element from stack to vector v             v[--m] = s.peek();             s.pop();         }         // printing result         for (Integer x : v) {             System.out.print(x + " ");         };         System.out.println("");     } // Driver code     public static void main(String[] args) {         int n = 5, k = 2;         int arr[] = {20, 10, 25, 30, 40};         deleteElements(arr, n, k);     } } // This code is contributed by PrinciRaj1992 ``` ## Python3 ```py # Function to delete elements def deleteElements(arr, n, k):     # create an empty stack st     st = []     st.append(arr[0])     # index to mantain the top      # of the stack     top = 0     count = 0     for i in range(1, n):         # pop till the present element          # is greater than stack's top         # element         while(len(st) != 0 and count < k                    and st[top] < arr[i]):             st.pop()             count += 1             top -= 1         st.append(arr[i])         top += 1     # print the remaining elements     for i in range(0, len(st)):         print(st[i], " ", end="") # Driver code k = 2 arr = [20, 10, 25, 30, 40]  deleteElements(arr, len(arr), k) # This code is contributed by himan085\. ``` ## C# ```cs // C# program to delete elements from array. using System; using System.Collections.Generic; class GFG {     // Function for deleting k elements     static void deleteElements(int []arr, int n, int k)      {         // Create a stack and push arr[0]         Stack<int> s = new Stack<int>();         s.Push(arr[0]);         int count = 0;         // traversing a loop from i = 1 to n         for (int i = 1; i < n; i++)         {             // condition for deleting an element             while (s.Count != 0 && s.Peek() < arr[i]                     && count < k)              {                 s.Pop();                 count++;             }             s.Push(arr[i]);         }         // Putting elements of stack in a vector         // from end to begin.         int m = s.Count;         int[] v = new int[m]; // Size of vector is m         while (s.Count != 0)          {             // push element from stack to vector v             v[--m] = s.Peek();             s.Pop();         }         // printing result         foreach (int x in v)          {             Console.Write(x + " ");         };         Console.Write("");     }     // Driver code     public static void Main()      {         int n = 5, k = 2;         int []arr = {20, 10, 25, 30, 40};         deleteElements(arr, n, k);     } } // This code is contributed by 29AjayKumar ``` **输出**： ``` 25 30 40 ``` * * * * * *