//sumA()和sumB()用于求从1到N之和
#include <iostream>
using namespace std;
int sumA(int n) {
    int sum = 0;
    for (int i = 1; i < n + 1; i++)
        sum += i;
    return sum;
}
int sumB(int n) {
    if (n == 1)
        return 1;
    else
        return n + sumB(n - 1);
}
int main() {
    int n = 0;
    cin >> n;
    cout << sumA(n) << " " << sumB(n) << endl;
    return 0;
}

//字符串反序
#include <iostream>
#include <string>
using namespace std;
string sReverse(string sIn) {
    if (sIn.length() <= 1) {
        return sIn;
    } else {
        return return ________ //此处填写代码
    }
}
int main() {
    string sIn;
    cin >> sIn;
    count << sReverse(sIn) << endl;
    return 0;
}

#include <iostream>
using namespace std;
// 递归实现汉诺塔，将N个圆盘从A通过B移到C
// 圆盘从底到顶，半径必须从大到小
void Hanoi(string A, string B, string C, int N) {
    if (N == 1) {
        cout << A << " -> " << C << endl;
    } else {
        Hanoi(A, C, B, N - 1);
        cout << A << " -> " << C << endl;
        ____________; //此处填写代码 
    }
}
int main() {
    Hanoi("甲", "乙", "丙", 3);
    return 0;
}

#include <iostream>
#include <vector>
#include <algorithm>

bool isOdd(int N) {
    return N % 2 == 1;
}
bool compare(int a, int b) {
    if (a % 2 == 0 && b % 2 == 1)
        return true;
    return false;
}
int main() {
    vector<int> 1stA; // 1stA是一个整型向量
    for (int i = 1; i < 100; i++)
        1stA.push_back(i);
    // 对1stA成员按比较函数执行结果排序
    sort(1stA.begin(), 1stA.end(), ________); // 此处填写代码1

    vector<int> 1stB;
    for (int i = 0; i < 1stA.size(); i++) // 1stB成员全为奇数
        if (________________) // 此处填写代码2
            1stB.push_back(1stA[i]);

    cout << "1stA: ";
    for (int i = 0; i < 1stA.size(); i++)
        cout << 1stA[i] << " ";
    cout << endl;

    cout << "1stB: ";
    for (int i = 0; i < 1stB.size(); i++)
        cout << 1stB[i] << " ";
    cout << endl;
    return 0;
}

// 在C++语言中，可以通过函数指针的形式，将一个函数作为另一个函数的参数。
// 具体来说：bool checkNum(bool (*Fx)(int), int N); 声明了一个函数，
// 其第一个参数是函数指针类型，指向一个接收一个int参数且返回值为bool的函数。
#include <iostream>
using namespace std;

bool isEven(int N) {
    return N % 2 == 0;
}
bool checkNum(bool (*Fx)(int), int N) {
    return Fx(N);
}
int main() {
    cout << checkNum(isEven, 10) << endl;
    return 0;
}

#include <iostream>
using namespace std;

bool isOdd(int N) {
    return N % 2 == 1;
}
int Square(int N) {
    return N * N;
}
bool checkNum(bool (*Fx)(int), int x) {
    return Fx(x);
}
int main() {
    cout << checkNum(isOdd, 10) << endl; // 输出行A
    cout << checkNum(Square, 10) << endl; // 输出行B
    return 0;
}

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

bool isPrimeA(int N) {
    if (N < 2)
        return false;
    for (int i = 2; i < N; i++)
        if (N % i == 0)
            return false;
    return true;
}
bool isPrimeB(int N) {
    if (N < 2)
        return false;
    int endNum = int(sqrt(N));
    for (int i = 2; i <= endNum; i++)
        if (N % i == 0)
            return false;
    return true;
}
int main() {
    cout << boolalpha;
    cout << isPrimeA(13) << " " << isPrimeB(13) << endl;
    return 0;
}

#include <iostream>
using namespace std;

void mergeSort(int* listData, int start, int end);
void merge(int* listData, int start, int middle, int end);

void mergeSort(int* listData, int start, int end) {
    if (start >= end)
        return;
    int middle = (start + end) / 2;
    mergeSort(listData, start, middle);
    mergeSort(listData, middle + 1, end);
    merge(listData, start, middle, end);
}
void merge(int* listData, int start, int middle, int end) {
    int leftSize = middle - start + 1;
    int rightSize = end - middle;

    int* left = new int[leftSize];
    int* right = new int[rightSize];
    for (int i = 0; i < leftSize; i++)
        left[i] = listData[start + i];
    for (int j = 0; j < rightSize; j++)
        right[j] = listData[middle + 1 + j];

    int i = 0, j = 0, k = start;
    while (i < leftSize && j < rightSize) {
        if (left[i] <= right[j]) {
            listData[k] = left[i];
            i++;
        } else {
            listData[k] = right[j];
            j++;
        }
        k++;
    }

    while (i < leftSize) {
        listData[k] = left[i];
        i++;
        k++;
    }
    while (j < rightSize) {
        listData[k] = right[j];
        j++;
        k++;
    }
    delete[] left;
    delete[] right;
}
int main() {
    int 1stA[] = {1, 3, 2, 7, 11, 5, 3};
    int size = sizeof(1stA) / sizeof(1stA[0]);

    mergeSort(1stA, 0, size - 1); // 对1stA执行归并排序

    for (int i = 0; i < size; i++)
        cout << 1stA[i] << " ";
    cout << endl;
    return 0;
}

#include <iostream>

class Node {
public:
    int Value;
    Node* Next;

    Node(int val, Node* Nxt = nullptr) {
        Value = Val;
        Next = Nxt;
    }
};

int main() {
    Node* firstNode = new Node(10);
    firstNode->Next = new Node(100);
    firstNode->Next->Next = new Node(111, firstNode);
    return 0;
}