From 2e126db1b80d2ac461721504a5efe82fd679fa96 Mon Sep 17 00:00:00 2001
From: Anjuna-Ramesh <57183849+Anjuna-Ramesh@users.noreply.github.com>
Date: Wed, 30 Oct 2019 20:51:05 +0530
Subject: [PATCH] Create lzw

---
 lzw | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 lzw

diff --git a/lzw b/lzw
new file mode 100644
index 0000000..738a832
--- /dev/null
+++ b/lzw
@@ -0,0 +1,82 @@
+#include <bits/stdc++.h> 
+using namespace std; 
+vector<int> encoding(string s1) 
+{ 
+	cout << "Encoding\n"; 
+	unordered_map<string, int> table; 
+	for (int i = 0; i <= 255; i++) { 
+		string ch = ""; 
+		ch += char(i); 
+		table[ch] = i; 
+	} 
+
+	string p = "", c = ""; 
+	p += s1[0]; 
+	int code = 256; 
+	vector<int> output_code; 
+	cout << "String\tOutput_Code\tAddition\n"; 
+	for (int i = 0; i < s1.length(); i++) { 
+		if (i != s1.length() - 1) 
+			c += s1[i + 1]; 
+		if (table.find(p + c) != table.end()) { 
+			p = p + c; 
+		} 
+		else { 
+			cout << p << "\t" << table[p] << "\t\t"
+				<< p + c << "\t" << code << endl; 
+			output_code.push_back(table[p]); 
+			table[p + c] = code; 
+			code++; 
+			p = c; 
+		} 
+		c = ""; 
+	} 
+	cout << p << "\t" << table[p] << endl; 
+	output_code.push_back(table[p]); 
+	return output_code; 
+} 
+
+void decoding(vector<int> op) 
+{ 
+	cout << "\nDecoding\n"; 
+	unordered_map<int, string> table; 
+	for (int i = 0; i <= 255; i++) { 
+		string ch = ""; 
+		ch += char(i); 
+		table[i] = ch; 
+	} 
+	int old = op[0], n; 
+	string s = table[old]; 
+	string c = ""; 
+	c += s[0]; 
+	cout << s; 
+	int count = 256; 
+	for (int i = 0; i < op.size() - 1; i++) { 
+		n = op[i + 1]; 
+		if (table.find(n) == table.end()) { 
+			s = table[old]; 
+			s = s + c; 
+		} 
+		else { 
+			s = table[n]; 
+		} 
+		cout << s; 
+		c = ""; 
+		c += s[0]; 
+		table[count] = table[old] + c; 
+		count++; 
+		old = n; 
+	} 
+} 
+int main() 
+{ 
+
+	string s = "WYS*WYGWYS*WYSWYSG"; 
+	vector<int> output_code = encoding(s); 
+	cout << "Output Codes are: "; 
+	for (int i = 0; i < output_code.size(); i++) { 
+		cout << output_code[i] << " "; 
+	} 
+	cout << endl; 
+	decoding(output_code); 
+}