北邮机试——huffman权值问题

我的Online Judge账号还没有这道题的访问权限（1172），这让我情何以堪，好在还是找到了题目，题目想做的比较好还是需要一些功底的。

做一下，马上就复试了，注释也没时间写，代码能看清楚：

/*
 * author: xuangong
 * time: 2013-4-9 21:42
 */
#include <stdio.h>
#include <stdlib.h>

typedef struct _huffmannode
{
    int data;
    struct _huffmannode *lchild;
    struct _huffmannode *rchild;
}huffmannode, *phuffmannode;

typedef struct _list
{
    phuffmannode node;
    struct _list * next;
}list, *plist;

plist init_list()
{
    plist head = (plist)malloc(sizeof(struct _list));
    head->next = head->node = NULL;
    return head;
}

void add_list(plist head, phuffmannode node)
{
    plist insert = (plist)malloc(sizeof(struct _list));
    insert->node = node;
    insert->next = NULL;
    if(head==NULL)
        printf("head is null\n");
    if(head!=NULL)
    {
        plist pre = head;
        head = head->next;
        while(head!=NULL && node->data > head->node->data)
        {
            pre = head;
            head = head->next;
        }
        insert->next = pre->next;
        pre->next = insert;
    }
}

void display(plist head)
{
    head = head->next;
    while(head!=NULL)
    {
        printf("%d ", head->node->data);
        head = head->next;
    }
    printf("\n");
}

phuffmannode get_list(plist head)
{
    plist temp = head->next;
    phuffmannode top = head->next->node;
    head->next = head->next->next;
    free(temp);
    return top;
}

phuffmannode create_huffmannode(plist li)
{
    phuffmannode lchild, rchild, node;
    if(li->next!=NULL && li->next->next == NULL)
        return get_list(li);
    while(li->next!=NULL && li->next->next!=NULL)
    {
        lchild = get_list(li);
        rchild = get_list(li);
        node = (phuffmannode)malloc(sizeof(struct _huffmannode));
        node->data = lchild->data + rchild->data;
        node->lchild  = lchild;
        node->rchild = rchild;
        add_list(li, node);
    }
    return get_list(li);
}

int traversetree(phuffmannode root, int level)
{
    if(root==NULL)
        return 0;
    if(root->lchild==NULL && root->rchild==NULL)
        return root->data*level;
    return traversetree(root->lchild ,level+1) + traversetree(root->rchild, level+1);
}

void destorytree(phuffmannode root)
{
    if(root==NULL)
        return;
    if(root->lchild==NULL && root->rchild==NULL)
    {
        free(root);
        root = NULL;
        return;
    }
    destorytree(root->lchild);
    destorytree(root->rchild);
}

int main()
{
    int count, i, data, level;
    phuffmannode node;
    level = 0;
    plist head = init_list();
    while(scanf("%d", &count)!=EOF)
    {
        for(i=0;i<count;i++)
        {
            scanf("%d", &data);
            node = (phuffmannode)malloc(sizeof(struct _huffmannode));
            node->data = data;
            node->lchild = node->rchild = NULL;
            add_list(head, node);
        }
        phuffmannode root = create_huffmannode(head);
        printf("This huffman tree is value is:%d\n", traversetree(root, level));
        destorytree(root);
    }
    return 0;
}

 上面是链表建树的办法，如果不建树，不用链表，仅仅为了完成这道题，今天看的方法真是帅呆了！

#include <stdio.h>
#include <stdlib.h>

int val[1001];

int cmp(const void * a,const void * b) //when the result is true "a>b" , a is after b
{
    return *(int *)a - *(int *)b;
}

int main()
{
    int n;
    int i;
    int ans;
    while(scanf("%d",&n) != EOF)
    {
        ans = 0;
        for(i = 0;i < n;i++) 
            scanf("%d",&val[i]);
        for(i = 1;i < n;i++)
        {
            qsort(&val[i - 1], n - i + 1, sizeof(val[0]), cmp);
            ans += val[i - 1] + val[i];
            val[i] += val[i - 1];
        }
        printf("%d\n",ans);
    }
    return 0;
}