ZOJ-1117

Huffman编码树构造，参考算法导论上的方法，用优先队列的话不难搞，但是由于对C++ STL完全不熟，查了N久API再加上参考大神代码才断断续续地写完，总算对priority_queue用法有了一定了解，下次应该不会这么坑了。。注意本题输入有AAAAAAAAAAAAAA这种串，要特殊处理下，否则WA

#include<cstdio>#include<queue>#include<string>#include<iostream>#include<map>#include<vector>using namespace std;namespace{int total;map<char, int> mp;struct Node{char c;int count;Node *left;Node *right;};struct cmp{bool operator()(Node* n1, Node* n2){return n1->count > n2->count;}};void dfs(Node *node, int depth){if (node->c)total += mp[node->c] * depth;if (node->left)dfs(node->left, depth + 1);if (node->right)dfs(node->right, depth + 1);}void destory(Node *node){if (node->left)destory(node->left);if (node->right)destory(node->right);delete node;}}int main(){string s;while (cin >> s, s != "END"){mp.clear();for (size_t i = 0; i < s.size(); i++)if (mp.find(s[i]) == mp.end())mp[s[i]] = 1;elsemp[s[i]]++;priority_queue<Node*, vector<Node*>, cmp> queue;for (map<char, int>::iterator it = mp.begin(); it != mp.end(); it++){Node *node = new Node();node->c = it->first;node->count = it->second;queue.push(node);}if (queue.size() == 1){Node *node = new Node();queue.push(node);}while (queue.size() > 1){Node *left = queue.top();queue.pop();Node *right = queue.top();queue.pop();Node *now = new Node();now->count = left->count + right->count;now->left = left;now->right = right;queue.push(now);}total = 0;dfs(queue.top(), 0);destory(queue.top());queue.pop();printf("%d %d %.1lf\n", s.size() * 8, total, s.size() * 8.0 / total);}return 0;}