Data commit

Task/Stern-Brocot-sequence/QBasic/stern-brocot-sequence.basic

@@ -0,0 +1,61 @@
+CONST max = 2000
+DIM SHARED stern(max + 2)
+
+FUNCTION gcd (x, y)
+    WHILE y
+        t = y
+        y = x MOD y
+        x = t
+    WEND
+    gcd = x
+END FUNCTION
+
+SUB SternBrocot
+    stern(1) = 1
+    stern(2) = 1
+
+    i = 2: n = 2: ub = UBOUND(stern)
+
+    DO WHILE i < ub
+        i = i + 1
+        stern(i) = stern(n) + stern(n - 1)
+        i = i + 1
+        stern(i) = stern(n)
+        n = n + 1
+    LOOP
+END SUB
+
+SternBrocot
+
+PRINT "The first 15 are: ";
+FOR i = 1 TO 15
+    PRINT stern(i); " ";
+NEXT i
+
+PRINT : PRINT
+PRINT "  Index   First nr."
+d = 1
+FOR i = 1 TO max
+    IF stern(i) = d THEN
+        PRINT USING " ######"; i; stern(i)
+        d = d + 1
+        IF d = 11 THEN d = 100
+        IF d = 101 THEN EXIT FOR
+        i = 0
+    END IF
+NEXT i
+
+PRINT : PRINT
+d = 0
+FOR i = 1 TO 1000
+    IF gcd(stern(i), stern(i + 1)) <> 1 THEN
+        d = gcd(stern(i), stern(i + 1))
+        EXIT FOR
+    END IF
+NEXT i
+
+IF d <> 0 THEN
+    PRINT "GCD of two consecutive members of the series up to the 1000th member is 1"
+ELSE
+    PRINT "The GCD for index "; i; " and "; i + 1; " = "; d
+END IF