递归与递归树

void printReverseString(const char* str){
    if(*str == '\0'){
        return;
    }
    printReverseString(str + 1);
    printf("%c", *str);
}

int main()
{
    const char* str = "Hello World";
    printReverseString(str);            // dlroW olleH

    return 0;
}

struct LinkNode{
    int data;
    struct LinkNode* next;
};

void printReverseLinkNode(struct LinkNode* header){
    if(header == NULL){
        return;
    }
    printReverseLinkNode(header->next);
    printf("%d\n", header->data);
}

int main()
{
    struct LinkNode* header = malloc(sizeof(struct LinkNode));
    struct LinkNode* node1 = malloc(sizeof(struct LinkNode));
    node1->data = 10;
    node1->next = NULL;
    struct LinkNode* node2 = malloc(sizeof(struct LinkNode));
    node2->data = 20;
    node2->next = NULL;
    struct LinkNode* node3 = malloc(sizeof(struct LinkNode));
    node3->data = 30;
    node3->next = NULL;
    header->next = node1;
    node1->next = node2;
    node2->next = node3;
    printReverseLinkNode(header->next);

    return 0;
}

void printNum(int num){
    if(num == 0){
        return;
    }
    int val = num / 10;
    printNum(val);
    printf("%d ", num % 10);
}

int main()
{
    int num = 8973;
    printNum(num);      // 8 9 7 3

    return 0;
}

int factorial(int n){
    if(n <= 1){
        return 1;
    }
    else{
        return n * factorial(n-1);
    }
}

int fibonacci(int n){
    if(n == 0) return 0;
    if(n == 1) return 1;
    return fibonacci(n-1) + fibonacci(n-2);
}

void move(char X, char Y){
    cout << "move " << X << " to " << Y << endl;
}
void hanoi(int n, char X, char Y, char Z){
    if(n <= 1){
        move (X, Z);
    }
    else{       
        hanoi(n-1, X, Z, Y);    // X 上最大的环不动，其他 n-1 个环移动到 Y
        move(X, Z);             // 移动最大的环到 Z，放好
        hanoi(n-1, Y, X, Z);    // 把 Y 上的 n-1 个环移动到 Z
    }
}