Added Dart code to find longest common substring between two strings

GGfIB2/BRbbeW.dart

@@ -0,0 +1,49 @@
+String findLongestCommonSubstring(String str1, String str2) {
+  var longestCommonSuffix = List.generate(str1.length+1, 
+                           (_) => List.generate(str2.length+1, (_) => 0, growable: false),
+                           growable: false);
+
+  int row=-1, col=-1, lcsLength=0;
+
+  // Find length of longest common substring
+  for (int i=1; i<=str1.length; i++) {
+    for (int j=1; j<=str2.length; j++) {
+      if (str1[i-1] == str2[j-1]) {
+        longestCommonSuffix[i][j] = longestCommonSuffix[i-1][j-1] + 1;
+        if (lcsLength < longestCommonSuffix[i][j]) {
+          lcsLength = longestCommonSuffix[i][j];
+          row = i;
+          col = j;
+        }
+      }
+    }
+  }
+
+  if(lcsLength == 0)
+    return "";
+
+
+  // Find longest common substring
+  var longestCommonSubstringList = List.filled(lcsLength, "");
+  while(longestCommonSuffix[row][col] != 0) {
+    longestCommonSubstringList[--lcsLength] += str1[row-1];
+    row--;
+    col--;
+  }
+
+  String longestCommonSubstring = longestCommonSubstringList.join("");
+
+  return longestCommonSubstring;
+}
+
+
+void main() {
+  String s1 = "coding is fun";
+  String s2 = "we need to enjoy coding";
+
+  String lcs = findLongestCommonSubstring(s1, s2);
+  if(lcs == "")
+    print("No common substring!");
+  else
+    print("Longest Common Substring => " + lcs);
+}