Data commit

Task/Longest-common-substring/Modula-2/longest-common-substring.mod2

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+MODULE LCS;
+FROM FormatString IMPORT FormatString;
+FROM Terminal IMPORT WriteString,WriteLn,Write,ReadChar;
+
+PROCEDURE WriteSubstring(s : ARRAY OF CHAR; b,e : CARDINAL);
+VAR i : CARDINAL;
+BEGIN
+    IF b=e THEN RETURN END;
+    IF e>HIGH(s) THEN e := HIGH(s) END;
+
+    FOR i:=b TO e DO
+        Write(s[i])
+    END
+END WriteSubstring;
+
+TYPE
+    Pair = RECORD
+        a,b : CARDINAL;
+    END;
+
+PROCEDURE lcs(sa,sb : ARRAY OF CHAR) : Pair;
+VAR
+    output : Pair;
+    a,b,len : CARDINAL;
+BEGIN
+    output := Pair{0,0};
+
+    FOR a:=0 TO HIGH(sa) DO
+        FOR b:=0 TO HIGH(sb) DO
+            IF (sa[a]#0C) AND (sb[b]#0C) AND (sa[a]=sb[b]) THEN
+                len := 1;
+                WHILE (a+len<HIGH(sa)) AND (b+len<HIGH(sb)) DO
+                    IF sa[a+len] = sb[b+len] THEN
+                        INC(len)
+                    ELSE
+                        BREAK
+                    END
+                END;
+                DEC(len);
+
+                IF len>output.b-output.a THEN
+                    output := Pair{a,a+len}
+                END
+            END
+        END
+    END;
+
+    RETURN output
+END lcs;
+
+VAR res : Pair;
+BEGIN
+    res := lcs("testing123testing", "thisisatest");
+    WriteSubstring("testing123testing", res.a, res.b);
+    WriteLn;
+
+    ReadChar
+END LCS.