如何从C ++中的集合中删除最后一个元素

给定一个 Set，任务是在 C++ 中从这个 Set 中删除最后一个元素。

例子：

Input: set = [10 20 30 70 80 90 100 40 50 60]
Output: 10 20 30 40 50 60 70 80 90

Input: set = [1 2 3 4 5]
Output: 1 2 3 4

集合是一种关联容器，其中每个元素都必须是唯一的，因为元素的值标识了它。元素的值一旦添加到集合中就不能修改，尽管可以删除和添加该元素的修改值。

Set 的最后一个元素可以通过传递 iterator来删除。

句法：

iterator erase (const_iterator positionOfElementToBeDeleted);

方法：通过将迭代器传递给擦除函数，可以轻松删除最后一个元素。要到达指向最后一个元素的迭代器，有两种方法：

1. 方法一：

   prev(setInt.end())

   下面是上述方法的实现：

   方案一：

   // C++ program to delete last element
   // of a Set by passing its iterator
     
   #include 
   #include 
   using namespace std;
     
   // Function to print the set
   void printSet(set myset)
   {
     
       // Get the iterator
       set::iterator it;
     
       // printing all the elements of the set
       for (it = myset.begin(); it != myset.end(); ++it)
           cout << ' ' << *it;
       cout << '\n';
   }
     
   // Function to delete last element of set
   // using method 1
   void deleteByMethod1(set myset)
   {
     
       // printing all the elements of the set
       cout << "\nSet originally: ";
       printSet(myset);
     
       // Get the iterator
       set::iterator it;
     
       // Get the positionOfElementToBeDeleted
       // using method 1
       it = prev(myset.end());
     
       // Erase the last element
       // currently pointed by the iterator
       myset.erase(it);
     
       // printing all the elements of the set
       cout << "Set after deletion: ";
       printSet(myset);
   }
     
   // Driver code
   int main()
   {
       set myset;
     
       // Get the set
       for (int i = 1; i < 10; i++)
           myset.insert(i * 10);
     
       // Method 1 to get positionOfElementToBeDeleted
       deleteByMethod1(myset);
     
       return 0;
   }
   

   输出：

   Set originally:  10 20 30 40 50 60 70 80 90
   Set after deletion:  10 20 30 40 50 60 70 80
   

2. 方法二：

   set::iterator it = setInt.end(); 
   --it;
   

   下面是上述方法的实现：

   方案二：

   // C++ program to delete last element
   // of a Set by passing its iterator
     
   #include 
   #include 
   using namespace std;
     
   // Function to print the set
   void printSet(set myset)
   {
     
       // Get the iterator
       set::iterator it;
     
       // printing all the elements of the set
       for (it = myset.begin(); it != myset.end(); ++it)
           cout << ' ' << *it;
       cout << '\n';
   }
     
   // Function to delete last element of set
   // using method 2
   void deleteByMethod2(set myset)
   {
     
       // printing all the elements of the set
       cout << "\nSet originally: ";
       printSet(myset);
     
       // Get the iterator
       set::iterator it;
     
       // Get the positionOfElementToBeDeleted
       // using method 2
       it = --myset.end();
     
       // Erase the last element
       // currently pointed by the iterator
       myset.erase(it);
     
       // printing all the elements of the set
       cout << "Set after deletion: ";
       printSet(myset);
   }
     
   // Driver code
   int main()
   {
       set myset;
     
       // Get the set
       for (int i = 1; i < 10; i++)
           myset.insert(i * 10);
     
       // Method 2 to get positionOfElementToBeDeleted
       deleteByMethod2(myset);
     
       return 0;
   }
   

   输出：

   Set originally:  10 20 30 40 50 60 70 80 90
   Set after deletion:  10 20 30 40 50 60 70 80