Link List

At first, i prepared to go through 《the introduction to algorithm》 ,however , i found some part of the book is difficult to understand; what’s more , i can’t borrow the book in the library. Then i found another book, 《algorithm in C》，which reveal most basic idea of some classical algorithm, so i decide to read this book firstly.

example 1:josephus funciton

#include<stdlib.h>
#include<stdio.h>
typedef struct node* link;
struct node
{
    int item;
    link next;
};

int main(int argc,char *argv[])
{
    int i, N, M;
    scanf("%d%d",&N,&M);
    node *t = new node,*x;
    x = t;
    t->item = 1;
    t->next = t;
    for (i = 2; i <= N; i++)
    {
        x->next = new node;
        x = x->next;
        x->item = i;
        x->next = t;
    }
    while (x != x->next)
    {
        for (i = 1; i < M; i++)
        {
            x = x->next;
        }
        x->next = x->next->next;
        N--;
    }
    printf("%d\n",x->item);
}

example2: reverse link list

#include<stdlib.h>
#include<stdio.h>
typedef struct node* link;
struct node
{
    int item;
    link next;
    node()
    {
        next = NULL;
    }
};

link reverse(link x)
{
    /*
    将y后节点的指针保存在t中，然后将y的链接指向r,再使r移到y,y移到t
    */
    link t, y = x, r = NULL;
    while (y != NULL)
    {
        t = y->next;
        y->next = r;
        r = y;
        y = t;
    }
    return r;
}

int main(int argc,char *argv[])
{
    int i, N, M;
    scanf("%d%d",&N,&M);
    node *t = new node,*x,*head;
    x = t;
    head = t;
    t->item = 1;
    t->next = t;
    for (i = 2; i <= N; i++)
    {
        x->next = new node;
        x = x->next;
        x->item = i;
    }
    node *newhead = reverse(head);
    while (newhead != NULL)
    {
        printf("%d ",newhead->item);
        newhead = newhead->next;
    }
}