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Task/Sorting-algorithms-Merge-sort/Liberty-BASIC/sorting-algorithms-merge-sort.liberty

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+    itemCount = 20
+    dim A(itemCount)
+    dim tmp(itemCount)    'merge sort needs additionally same amount of storage
+
+    for i = 1 to itemCount
+        A(i) = int(rnd(1) * 100)
+    next i
+
+    print "Before Sort"
+    call printArray itemCount
+
+    call mergeSort 1,itemCount
+
+    print "After Sort"
+    call printArray itemCount
+end
+
+'------------------------------------------
+sub mergeSort start, theEnd
+    if theEnd-start < 1 then exit sub
+    if theEnd-start = 1 then
+        if A(start)>A(theEnd) then
+            tmp=A(start)
+            A(start)=A(theEnd)
+            A(theEnd)=tmp
+        end if
+        exit sub
+    end if
+    middle = int((start+theEnd)/2)
+    call mergeSort start, middle
+    call mergeSort middle+1, theEnd
+    call merge start, middle, theEnd
+end sub
+
+sub merge start, middle, theEnd
+    i = start: j = middle+1: k = start
+    while i<=middle OR j<=theEnd
+        select case
+        case i<=middle AND j<=theEnd
+            if A(i)<=A(j) then
+                tmp(k)=A(i)
+                i=i+1
+            else
+                tmp(k)=A(j)
+                j=j+1
+            end if
+            k=k+1
+        case i<=middle
+            tmp(k)=A(i)
+            i=i+1
+            k=k+1
+        case else    'j<=theEnd
+            tmp(k)=A(j)
+            j=j+1
+            k=k+1
+        end select
+    wend
+
+    for i = start to theEnd
+        A(i)=tmp(i)
+    next
+end sub
+
+'===========================================
+sub printArray itemCount
+    for i = 1 to itemCount
+        print using("###", A(i));
+    next i
+    print
+end sub