huffman code

讲得不错：

11111

Poj,3253

//Huffman每次选最小的两个加和最小，最后结果最小。

#include <iostream>
#include <queue>
#include <vector>
#include <algorithm>
#include <cstdio>

#define ll long long
#define N 20005
using namespace std;

int n;
class HTree
{
    public :
    HTree* left;
    HTree* right;
    int weight;
    
    HTree(){left = right = NULL; weight=0;}
    HTree(HTree* l,HTree* r,int w){left = l;    right = r;    weight=w;}
    ~HTree(){delete left; delete right;}
};

class Compare_tree
{
public:
    bool operator () (HTree* t1, HTree* t2)
    {
        return t1->weight> t2->weight;
    }
};

ll BuildTree(int *frequency,ll charge)
{
    priority_queue<HTree*,vector<HTree*>,Compare_tree> QTree;
    
    for (int i=0;i<n;i++)
    {
        if(frequency[i])
            QTree.push(new HTree(NULL,NULL,frequency[i]));
    }
    
    while (QTree.size()>1)
    {
        HTree* lc  = QTree.top();
        QTree.pop();
        HTree* rc = QTree.top();
        QTree.pop();
        charge+=lc->weight+rc->weight;
        HTree* parent = new HTree(lc,rc,lc->weight+rc->weight);
        QTree.push(parent);
    }
    return charge;
}

int main()
{
    int L;
    int freq[N] = {0};
    scanf("%d",&n);
    for(int i=0;i<n;i++)
    {
        scanf("%d",&L);
        freq[i]=L;
    }
    ll result=BuildTree(freq,0);
    printf("%lld
",result);
    return 0;
}

#include <iostream>
#include <queue>
#include <algorithm>
#include <cstdio>

#define ll long long
#define N 20005
using namespace std;

int n;
struct Node
{
    int w;
    bool operator<(const Node& a)const
    {
        return w>a.w;
    }
};

int main()
{
    priority_queue<Node> qu;
    Node root;
    scanf("%d",&n);
    for(int i=0;i<n;i++)
    {
        
        scanf("%d",&root.w);
        qu.push(root);
    }
    ll result=0;
    while(qu.size()>1)
    {
        int l=qu.top().w;qu.pop();
        int r=qu.top().w;qu.pop();
        root.w=l+r;
        result+=root.w;
        qu.push(root);
    }
    printf("%lld
",result);
    return 0;
}

 zoj,2399

注意Huffman的数据可能很大，所以注意weight和最后的和都用longlong

Huffman编码的长度等于 w[i]*l[i]就是每次建一次树的跟节点的权值

#include <iostream>
#include <queue>
#include <cstdio>

using namespace std;

typedef long long ll;

struct node
{
    ll w;
    
    bool operator<(const node& a)const
    {
        return w>a.w;
    }
};


int main()
{
    int size;
    scanf("%d",&size);
    while(size--)
    {
        int n;
        priority_queue<node> qp;
        scanf("%d",&n);
        for(int i=0;i<n;i++)
        {
            int w;
            cin>>w;
            node now;
            now.w=w;
            qp.push(now);
        }
        ll ans=0;
        while(qp.size()>1)
        {
            ll l=qp.top().w;qp.pop();
            ll r=qp.top().w;qp.pop();
            
            node now1;
            now1.w=l+r;
            qp.push(now1);
            
            ans+=now1.w;
        }
        
        printf("%lld
",ans);
        if(size)
            printf("
");
    }
    return 0;
}

poj,1521

学校系统真是不敢恭维，我感觉在针对我。。。。

交了一个小时都wa，我之后无可奈何跑到poj上去交，一下就过了。。我真的见了鬼了

#include <cstdio>
#include <iostream>
#include <string>
#include <queue>
#include <cstring>
#include <cstdlib>

using namespace std;
const int maxn=256;
struct Node
{
    int weight;
    
    bool operator<(const Node& a)const
    {
        return weight>a.weight;
    }
};


int main()
{
    char s[maxn];
    
    while(gets(s))
    {
        if(!strcmp(s,"END"))
            break;
        int freq[maxn]={0};
        int cnt=strlen(s);
        priority_queue<Node> pq;
        for(int i=0;i<cnt;i++)
        {
            freq[s[i]]++;
        }
        for(int i=0;i<200;i++)
        {
            Node now;
            if(freq[i])
            {
                now.weight=freq[i];
                pq.push(now);
                freq[i]=0;
            }
        }
        
        int ans=0;
        while(pq.size()>1)
        {
            int l=pq.top().weight;pq.pop();
            int r=pq.top().weight;pq.pop();
            
            Node now;
            now.weight=l+r;
            pq.push(now);
            ans+=now.weight;
        }
        if(!ans)
            ans=cnt;
        while(!pq.empty())
            pq.pop();
        printf("%d %d %.1lf
",cnt*8,ans,double((double)(8*cnt)/ans));
    }
    return 0;
}