Merge pull request algorithm-visualizer#186 from archie94/longestCommonSubsequence

TornjV · web-flow · commit aba55386b433 · 2016-06-17T22:34:06.000+02:00
Longest common subsequence
diff --git a/algorithm/category.json b/algorithm/category.json
@@ -19,6 +19,7 @@
          "integer_partition": "Integer Partition",
          "knapsack_problem": "Knapsack Problem",
          "longest_increasing_subsequence": "Longest Increasing Subsequence",
+         "longest_common_subsequence": "Longest Common Subsequence",
          "max_subarray": "Maximum Subarray",
          "max_sum_path": "Maximum Sum Path",
          "pascal_triangle": "Pascal's Triangle",
diff --git a/algorithm/dp/longest_common_subsequence/basic/code.js b/algorithm/dp/longest_common_subsequence/basic/code.js
@@ -0,0 +1,36 @@
+var i,j;
+
+// Build the memo table in bottom up fashion 
+ for( i = 0; i <= m; i++ ) {
+ 	for( j = 0; j <= n; j++ ) {
+ 		if ( i === 0 || j === 0 ) {
+ 			A[i][j] = 0;
+ 		} else if ( string1[i-1] == string2[j-1] ) {
+ 			tracer1._select ( i-1 )._wait ();
+ 			tracer2._select ( j-1 )._wait ();
+ 			tracer3._select ( i-1, j-1 )._wait ();
+ 			
+ 			A[i][j] = A[i-1][j-1] + 1;
+ 			
+ 			tracer1._deselect ( i-1 );
+ 			tracer2._deselect ( j-1 );
+ 			tracer3._deselect ( i-1, j-1 );
+ 		} else {
+ 			tracer3._select ( i-1, j )._wait ();
+ 			tracer3._select ( i, j-1 )._wait ();
+ 			
+ 			if( A[i-1][j] > A[i][j-1] ) {
+ 				A[i][j] = A[i-1][j];
+ 			} else {
+ 				A[i][j] = A[i][j-1];
+ 			}
+ 			
+ 			tracer3._deselect ( i-1, j );
+ 			tracer3._deselect ( i, j-1 );
+ 		}
+ 		tracer3._notify ( i, j , A[i][j] )._wait ();
+ 		tracer3._denotify( i, j );
+ 	}
+ }
+
+ logger._print ( 'Longest Common Subsequence is ' + A[m][n] );
diff --git a/algorithm/dp/longest_common_subsequence/basic/data.js b/algorithm/dp/longest_common_subsequence/basic/data.js
@@ -0,0 +1,13 @@
+var string1 = 'AGGTAB';
+var string2 = 'GXTXAYB';
+var m = string1.length;
+var n = string2.length;
+var A = new Array (m+1);
+for (var i = 0; i < m+1; i++ ) {
+	A[i] = new Array (n+1);
+}
+
+var tracer1 = new Array1DTracer ( 'String 1')._setData ( string1 );
+var tracer2 = new Array1DTracer ( 'String 2')._setData ( string2 );
+var tracer3 = new Array2DTracer ( 'Memo Table')._setData ( A );
+var logger = new LogTracer ();
diff --git a/algorithm/dp/longest_common_subsequence/desc.json b/algorithm/dp/longest_common_subsequence/desc.json
@@ -0,0 +1,13 @@
+{
+  "Longest Common Subsequence": "The longest common subsequence (LCS) problem is the problem of finding the longest subsequence common to all sequences in a set of sequences (often just two sequences)." ,
+  "Complexity": {
+    "time": "O(mn)",
+    "space": "O(mn)"
+  },
+  "References": [
+    "<a href='https://en.wikipedia.org/wiki/Longest_common_subsequence_problem'>Wikipedia</a>"
+  ],
+  "files": {
+    "basic": "Longest common subsequence"
+  }
+}
