Question

我正在尝试删除堆栈中的最后N-1个元素，但是删除了第一个N-1。

这是程序的输出：

8
10
4
9
1
3
5
9
4
10

如果我们选择值为1的键“ 5”，则应将其后的所有元素从堆栈中删除，而所有先前的元素都将被删除。

删除元素的过程位于函数find_enth_from_bottom（）;

#include <iostream>
#include <stack>
using namespace std;

stack <int> stek;

void change_enth_from_bottom(stack <int>& smack, int en, int newvalue);
int find_enth_from_bottom(stack <int>& smack, int en);

int find_enth_from_bottom(stack <int>& smack, int en) {
    long size = smack.size();

    if (size < en) {
         return -1;
    }

    for (int i = 0; i < size - en; i++) {
        smack.pop();
    }

    return smack.top();
}

void change_enth_from_bottom(stack <int>& smack, int en, int newvalue) {
    find_enth_from_bottom(smack, en);
    smack.pop();
    smack.push(newvalue);
}

int main() {
    int position, value, counter = 0;

    for (int i = 1; i <= 10; i++) {
        int k_val = rand() % 10 + 1;
        cout << i << ". " << k_val << endl;
        stek.push(k_val);
    }

    cout << "Enter position: "; cin >> position;
    cout << endl << "Enter new value: "; cin >> value;

    change_enth_from_bottom(stek, position, value);
    cout << "The value of the element with position " << position << " is now changed to " << find_enth_from_bottom(stek, position) << endl;

    cout << "New stack interface" << endl;

    while(!stek.empty()) {
        counter++;
        int a = stek.top();
        stek.pop();
        cout << counter << ". " << a << endl;
    }

    return 0;
}

Answer 1

您可以在基础容器中进行任何操作。

#include <iostream>
#include <stack>

using container_t = std::stack<int>::container_type;

namespace detail
{
    class stack_access : std::stack<int>
    {
    public:
        using stack::c;
    };
}

constexpr container_t std::stack<int>::* container_ptr = &detail::stack_access::c;

int find_enth_from_bottom(std::stack<int> & stack, int en) {
    return (stack.*container_ptr)[stack.size() - en];
}

void change_enth_from_bottom(std::stack<int> & stack, int en, int newvalue) {
    (stack.*container_ptr)[stack.size() - en] = newvalue;
}

int main() {
    using std::cin;
    using std::cout;
    using std::endl;

    std::stack<int> stack;

    for (int i = 1; i <= 10; i++) {
        int k_val = rand() % 10 + 1;
        cout << i << ". " << k_val << endl;
        stack.push(k_val);
    }

    int position, value, counter = 0;

    cout << "Enter position: "; cin >> position;
    cout << endl << "Enter new value: "; cin >> value;

    change_enth_from_bottom(stack, position, value);
    cout << "The value of the element with position " << position << " is now changed to " << find_enth_from_bottom(stack, position) << endl;

    cout << "New stack interface" << endl;

    while(!stack.empty()) {
        counter++;
        int a = stack.top();
        stack.pop();
        cout << counter << ". " << a << endl;
    }

    return 0;
}

Note: Failed to read get kotlin metadata for ...etc, and type converter

如何在C ++中更改堆栈的迭代

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