西安交通大学915-2017-编程1

#include <iostream>
using namespace std;

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

bool FindReverseKthInLinkedList(ListNode* head, int k) {
    auto p = head;
    
    // 计算链表的长度  不包含头节点，只计算有效的节点
    int n = 0;
    while (p->next) {
        n++;
        p = p->next;
    }

    int cnt = n - k + 1;
    auto q = head->next;
    while (--cnt && q) {
        q = q->next;
    }
    if (!q) {
        return false;
    }
    cout << q->data << endl;
    return true;
}

void Print(ListNode* root) {
    if (!root) {
        return;
    }
    auto p = root->next;
    while (p) {
        cout << p->data << " ";
        p = p->next;
    }
    cout << endl;
}

int main() {
    // [10, 20, 30, 40, 50, 60]
    ListNode a, b, c, d, e, f;
    a.data = 10;
    b.data = 20;
    c.data = 30;
    d.data = 40;
    e.data = 50;
    f.data = 60;
    ListNode root;
    root.next = &a;
    a.next = &b;
    b.next = &c;
    c.next = &d;
    d.next = &e;
    e.next = &f;
    f.next = nullptr;
    Print(&root);
    FindReverseKthInLinkedList(&root, 1);
    FindReverseKthInLinkedList(&root, 2);
    FindReverseKthInLinkedList(&root, 3);
    FindReverseKthInLinkedList(&root, 4);
    FindReverseKthInLinkedList(&root, 5);
    FindReverseKthInLinkedList(&root, 6);
    return 0;
}