1 //用优先队列求huffman编码中的WPL
 2 #include <iostream>
 3 using std::cin;
 4 using std::cout;
 5 using std::endl;
 6 using std::swap;
 7 
 8 template <typename Type> class Heap {
 9 private:
10     Type *data;
11     int size;
12     void update(int pos, int n) {
13         int lchild = 2 * pos + 1, rchild = 2 * pos + 2;
14         int max_value =http://www.mamicode.com/ pos;
15         if (lchild < n && data[lchild] < data[max_value]) {
16             max_value =http://www.mamicode.com/ lchild;
17         }
18         if (rchild < n && data[rchild] < data[max_value]) {
19             max_value =http://www.mamicode.com/ rchild;
20         }
21         if (max_value != pos) {
22             swap(data[pos], data[max_value]);
23             update(max_value, n);
24         }
25     }
26 public:
27     Heap(int length_input) {
28         data = http://www.mamicode.com/new Type[length_input];
29         size = 0;
30     }
31     ~Heap() {
32         delete[] data;
33     }
34     void push(Type value) {
35         data[size] = value;
36         int current = size;
37         int father = (current - 1) / 2;
38         while (data[current] < data[father]) {
39             swap(data[current], data[father]);
40             current = father;
41             father = (current - 1) / 2;
42         }
43         size++;
44     }
45     Type top() {
46         return data[0];
47     }
48     void pop() {
49         swap(data[0], data[size - 1]);
50         size--;
51         update(0, size);
52     }
53     int heap_size() {
54         return size;
55     }
56 };
57 int main() {
58     int n,value,ans=0;
59     cin>>n;
60     Heap<int> heap(n);
61     for(int i=1;i<=n;i++){
62         cin>>value;
63         heap.push(value);
64     }
65     if(n==1){
66         ans+=heap.top();
67     }
68     while(heap.heap_size()>1){
69         int a=heap.top();
70         heap.pop();
71         int b=heap.top();
72         heap.pop();
73         //将小根堆最前面的两个元素,即最小的两个元素合并
74         //并把合成的树押回队列中
75         ans=ans+a+b;
76         heap.push(a+b);
77     }
78     cout<<ans<<endl;
79     return 0;
80 }