Data update

Task/Binary-search/Modula-2/binary-search.mod2

@@ -0,0 +1,70 @@
+MODULE BinarySearch;
+
+FROM STextIO IMPORT
+  WriteLn, WriteString;
+FROM SWholeIO IMPORT
+  WriteInt;
+
+TYPE
+  TArray = ARRAY [0 .. 9] OF INTEGER;
+
+CONST
+  A = TArray{-31, 0, 1, 2, 2, 4, 65, 83, 99, 782}; (* Sorted data *)
+
+VAR
+  X: INTEGER;
+
+PROCEDURE DoBinarySearch(A: ARRAY OF INTEGER; X: INTEGER): INTEGER;
+VAR
+  L, H, M: INTEGER;
+BEGIN
+  L := 0; H := HIGH(A);
+  WHILE L <= H DO
+    M := L + (H - L) / 2;
+    IF A[M] < X THEN
+      L := M + 1
+    ELSIF A[M] > X THEN
+      H := M - 1
+    ELSE
+      RETURN M
+    END
+  END;
+  RETURN -1
+END DoBinarySearch;
+
+PROCEDURE DoBinarySearchRec(A: ARRAY OF INTEGER; X, L, H: INTEGER): INTEGER;
+VAR
+  M: INTEGER;
+BEGIN
+  IF H < L THEN
+    RETURN -1
+  END;
+  M := L + (H - L) / 2;
+  IF A[M] > X THEN
+    RETURN DoBinarySearchRec(A, X, L, M - 1)
+  ELSIF A[M] < X THEN
+    RETURN DoBinarySearchRec(A, X, M + 1, H)
+  ELSE
+    RETURN M
+  END
+END DoBinarySearchRec;
+
+PROCEDURE WriteResult(X, IndX: INTEGER);
+BEGIN
+  WriteInt(X, 1);
+  IF IndX >= 0 THEN
+    WriteString(" is at index ");
+    WriteInt(IndX, 1);
+    WriteString(".")
+  ELSE
+    WriteString(" is not found.")
+  END;
+  WriteLn
+END WriteResult;
+
+BEGIN
+  X := 2;
+  WriteResult(X, DoBinarySearch(A, X));
+  X := 5;
+  WriteResult(X, DoBinarySearchRec(A, X, 0, HIGH(A)));
+END BinarySearch.