代码改变世界

ZOJ1117 第一次写赫夫曼编码

2013-05-19 13:57  凝月流风  阅读(211)  评论(0)    收藏  举报 
 

1 #include <stdio.h>
 2 #include <queue>
 3 #include <iostream>
 4 using namespace std;
 5 struct Node {
 6     int f;
 7  //   int height;
 8     int parent;
 9     bool visited;
10 }node[100];
11 
12 int num, r;
13 void getSmallestTwo (int &t1, int &t2){
14     int i, min = 99999999;
15     for (i = 0; i < num+r; i++) {
16         if (!node[i].visited && node[i].f < min) {
17             min = node[i].f;
18             t1 = i;
19         }
20     }
21     min = 99999999;
22     for (i = 0; i < num+r; i++) {
23         if (!node[i].visited && node[i].f < min && i != t1) {
24             min = node[i].f;
25             t2 = i;
26         }
27     }
28 }
29 
30 int getHeight(int x) {
31    int i = x, height = 0;
32    while(node[i].parent != -1) {
33        height++;
34        i = node[i].parent;
35    }
36    return height;
37 } 
38 int main() {
39     string str;
40     int i, oribit, nowbit;
41     double ratio;
42     while (cin>>str && str != "END") {
43         int a[27] = {0};
44         oribit = 8 * str.size();
45         nowbit = 0;
46         for (i = 0; i < 100; i++) {
47             node[i].f = 0;
48             node[i].visited = 0;
49        //     node[i].height = 0;
50             node[i].parent = -1;
51         }
52         for (i = 0; i < str.size(); i++) {
53             if (str[i] == '_') {
54                 a[26]++;
55             } else {
56                 a[str[i]-65]++;
57             }
58         }
59         int j = 0;
60         for (i = 0; i < 27; i++) {
61             if (a[i]) 
62                 node[j++].f = a[i];
63         }
64         num = j;
65    //     cout << num << endl;
66         if (num > 1) {
67             for ( r = 0; r < num-1; r++) {   //n-1轮即可构建赫夫曼编码树 
68                  int t1, t2;
69                  getSmallestTwo(t1, t2);
70                  node[t1].visited = 1;    //标记为遍历过，相当于从队列中删掉，避免重新比较 
71                  node[t2].visited = 1;
72                  node[t1].parent = num + r;   //不断增加节点数 
73                  node[t2].parent = num + r;
74                  node[num+r].f = node[t1].f + node[t2].f;
75             }
76             for (i = 0; i < num; i++) {
77                  int height = getHeight(i);  //获取节点高度 
78             //     cout << height << endl;
79                  nowbit += node[i].f * height;   //加上每个几点的高度和频数乘积 
80             }
81         } else {
82             nowbit = str.size();;
83         }
84         fdsc
85         ratio = (double)oribit / nowbit;
86         printf("%d %d %.1lf\n", oribit, nowbit, ratio);
87     }
88     return 0;
89 }