Huffman_Coding_&_Activity_Selection_474

Activity_Selection_474.cpp

@@ -0,0 +1,42 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+bool comp(pair<int,int>i,pair<int,int>j){
+    return i.second<j.second;
+}
+
+int main()
+{
+
+      int s[11]={0,1,2,3,3,5,5,6,8,8,12};           // Start time
+      int f[11]={6,4,14,5,9,7,9,10,11,12,16};       // Finish time
+      vector<pair<int,int>>vec(11);
+      cout<<"Start time of activities: "<<endl;
+      for(int i=0;i<11;i++){
+          vec[i].first=s[i];
+          cout<<vec[i].first<<" ";
+      }
+      cout<<"\nEnd time of activities: "<<endl;
+      for(int i=0;i<11;i++){
+          vec[i].second=f[i];
+          cout<<vec[i].second<<" ";
+      }
+
+      sort(vec.begin(),vec.end(),comp);		// Sorting activities based on Finish time in increasing order
+      vector<pair<int,int>>v;
+      v.push_back(vec[0]);
+      pair<int,int>current=vec[0];
+      for(int j=1;j<11;j++){
+          if(vec[j].first > current.second){
+              v.push_back(vec[j]);
+              current=vec[j];
+          }
+      }
+      vector<pair<int,int>>::iterator i;
+      cout<<"\nFollowing activities are selected- "<<endl;
+      for(i=v.begin();i!=v.end();i++){
+          cout<<"("<<(*i).first<<","<<(*i).second<<"), ";
+      }
+      cout<<endl;
+  return 0;
+}

Huffman_Coding_474.py

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+string = 'BCAADDDCCACACAC'
+
+
+# Creating tree nodes
+class NodeTree(object):
+
+    def __init__(self, left=None, right=None):
+        self.left = left
+        self.right = right
+
+    def children(self):
+        return (self.left, self.right)
+
+    def nodes(self):
+        return (self.left, self.right)
+
+    def __str__(self):
+        return '%s_%s' % (self.left, self.right)
+
+
+# Main function implementing huffman coding
+def huffman_code_tree(node, left=True, binString=''):
+    if type(node) is str:
+        return {node: binString}
+    (l, r) = node.children()
+    d = dict()
+    d.update(huffman_code_tree(l, True, binString + '0'))
+    d.update(huffman_code_tree(r, False, binString + '1'))
+    return d
+
+
+# Calculating frequency
+freq = {}
+for c in string:
+    if c in freq:
+        freq[c] += 1
+    else:
+        freq[c] = 1
+
+freq = sorted(freq.items(), key=lambda x: x[1], reverse=True)
+
+nodes = freq
+
+while len(nodes) > 1:
+    (key1, c1) = nodes[-1]
+    (key2, c2) = nodes[-2]
+    nodes = nodes[:-2]
+    node = NodeTree(key1, key2)
+    nodes.append((node, c1 + c2))
+
+    nodes = sorted(nodes, key=lambda x: x[1], reverse=True)
+
+huffmanCode = huffman_code_tree(nodes[0][0])
+
+print(' Char | Huffman code ')
+print('----------------------')
+for (char, frequency) in freq:
+    print(' %-4r |%12s' % (char, huffmanCode[char]))