链表逆序 【经典题目】

/*************************************************************************
    > File Name: code01.cpp
    > Author: Jeremy Wu
    > Created Time: Thu 04 Jun 2015 07:48:19 PM CST
    > Function: Linklist reverse
 ************************************************************************/

#include <iostream>
#include <cmath>
#include <ctime>
#include <algorithm>

using namespace std;

struct Linklist {
    int key;
    Linklist * next;
};

Linklist * init (int num) {
    srand ((int)time (NULL));
    Linklist * head = new Linklist;
    head->key = rand () % 100;
    Linklist * p = head;
    while (num--) {
        Linklist * cur = new Linklist;
        cur->key = rand () % 100;
        p->next = cur;
        p = cur;
    }
    p->next = NULL;
    return head;
}

void print (Linklist * head) {
    int count = 0;
    while (head != NULL) {
        //cout << ++count << ": " << head->key << endl;
        cout << " " << head->key << " -> ";
        head = head->next;
    }
}

Linklist * linkReverse (Linklist * head) {
    if (head == null)    return null;
    Linklist * cur = NULL;
    Linklist * pre = NULL;
    while (head != NULL) {
        cur = head;        //assign cur
        head = head->next;    //traverse
        cur->next = pre;    //realize reverse
        pre = cur;        //assign pre
    }
    return cur;
}

int main () {

    Linklist * head;
    head = init (7);

    print (head);
    cout << endl<<endl;

    head = linkReverse (head);
    print (head);

    return 0;
}