https://robark.gitlab.io/huffman/index.htmlHuffman Coding Lossless compressionHugoen-usMon, 28 Jun 2021 19:36:20 +0000https://robark.gitlab.io/huffman/example/index.htmlWed, 23 Jun 2021 23:14:47 +0000https://robark.gitlab.io/huffman/example/index.htmlHuffman Coding example of “mississippi river” Algorithm: -combine last 2 nodes of linked list to create a binary tree. -root node string is concatenation of last node + second last node strings -root node sum is sum of last node + second last node integers -insert root node of new binary tree into linked list (insertion is sorted by integer then sub sorted by string if integers are equal) -repeat until only 1 node left in linked list.https://robark.gitlab.io/huffman/solution/index.htmlMon, 28 Jun 2021 19:36:20 +0000https://robark.gitlab.io/huffman/solution/index.htmlHuffman Coding solution to generate binary tree and code for each unique char in string I fixed having duplicate functions tinsert and linsert by having map2LL function create a new node then pass the new node to linsert. #include <iostream> #include <map> #include <vector> #include <algorithm> using namespace std; struct node{ node(string , int , node* , node* , node*); string str; int num; node* next; node* left; node* right; }; node::node(string s, int i, node* n=0, node* l=0, node* r=0){ str = s; num = i; next = n; left = l; right = r; } bool paircmp(pair <string , int> &a, pair <string, int> &b){ return a.second > b.second; } vector <pair <string, int> > map2VecPair( map < char, int> cimap){ //returns sorted vector of pairs of leaf nodes in map vector < pair<string, int> > nodeVec; map<char,int>::iterator i; for ( i = cimap.begin(); i != cimap.end(); i++ ) { pair <string, int> pr; pr.first=i->first; pr.second=i->second; nodeVec.push_back(pr); } sort(nodeVec.begin(), nodeVec.end(), paircmp); return nodeVec; } void printLL(node* nd){ //print linked list if (nd == 0) return; cout<< nd->str <<":"<<nd->num<<" , "; printLL(nd->next); } int lsize(node* nd){ //return size of linked list if (nd == 0) return 0; return 1 + lsize(nd->next); } void linsert(node* &p, node* &root){ //insert node p into linked list (sorted) if (root == 0) { root = p; return; } else if (p->num < root->num) { node* temp= root; root = p; root->next = temp; return; } else if (p->num == root->num) { if (p->str > root->str) { node* temp= root; root = p; root->next = temp; return; } else { linsert(p, root->next);//equal num but str is bigger return; } } else //p->num < root->num { linsert(p, root->next); return; } } void gentree(node* &root){ //convert first two nodes of linked list into a new binary tree //and insert top node of new tree back into linked list (sorted) if (lsize(root) < 2) { return; //safety check } string concat= root->str + (root->next)->str; int sum = root->num + (root->next)->num; node* p = new node(concat, sum); p->left = root; p->right = root->next; root = (root->next)->next; //third node is now the new root in the list linsert(p, root); } void freenode(node* n){ //free binary tree memory if (n == 0) return; freenode(n->left); freenode(n->right); delete n; } string gencode(string s, node* &root){ // generate bit string of 1's and 0's that represent path down binary tree // to leaf node if (s == root->str) return (""); else if (((root->left)->str).find(s) != string::npos) //found s in left tree { return "0"+gencode(s, root->left); } else { return "1"+gencode(s, root->right); } } map <char, int> genUniqChars(string text){ //generate map of key:unique chars with value: associated int occurance map < char, int > cimap; for (unsigned int x=0; x < text.size() ;x++) { if ( cimap.find(text[x]) == cimap.end() ) //not found { cimap[text[x]] = 1; } else { cimap[text[x]] = cimap[text[x]] + 1; } } return cimap; } void map2LL(node* &root, map <char , int> cimap){ //convert map of char / int to sorted linked list map<char,int>::iterator i; for ( i = cimap.begin(); i != cimap.end(); i++ ) { string s(1, i->first); //alternate string ctor to fill string with n(arg1) consecutive chars(arg2) node* p= new node(s, i->second); linsert(p, root); } } int main(){ string text("mississippi river"); //getline(cin, text); //cout << text << endl; map < char, int > cimap = genUniqChars(text); node* root(0); map2LL(root, cimap); //generate binary tree while (lsize(root) >1) { cout<<"LINKED LIST: "; printLL(root); cout<<endl; gentree(root); cout<<endl; cout<<"TREE: "; } printLL(root); cout<<endl; vector <pair <string, int> > pv = map2VecPair(cimap); for (auto it : pv) { cout << it.first << " " << it.second << " : "<< gencode(it.first, root)<<endl; } cout<<endl; freenode(root); return 0; }