Data update

Task/Sorting-algorithms-Radix-sort/Pluto/sorting-algorithms-radix-sort.pluto

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+require "table2"
+
+-- Counting sort of 'a' according to the digit represented by 'exp'.
+local function count_sort(a, exp)
+    local n = #a
+    local output = table.rep(n, 0)
+    local count  = table.rep(10, 0)
+    for i = 1, n do
+        local t = math.trunc(a[i] / exp) % 10
+        count[t + 1] += 1
+    end
+    for i = 1, 9 do count[i + 1] += count[i] end
+    for i = n, 1, -1 do
+        local t = math.trunc(a[i] / exp) % 10
+        output[count[t + 1]] = a[i]
+        count[t + 1] -= 1
+    end
+    for i = 1, n do a[i] = output[i] end
+end
+
+-- Sorts 'a' in place.
+local function radix_sort(a)
+    -- Check for negative elements.
+    local min = a:min()
+    -- If there are any, increase all elements by -min.
+    if min < 0 then
+        for i = 1, #a do a[i] -= min end
+    end
+    -- Now get the maximum to know number of digits
+    local max = a:max()
+    -- Do counting sort for each digit
+    local exp = 1
+    while math.trunc(max / exp) > 0 do
+        count_sort(a, exp)
+        exp *= 10
+    end
+    -- If there were negative elements, reduce all elements by -min.
+    if min < 0 then
+        for i = 1, #a do a[i] += min end
+    end
+end
+
+local aa =  {{4, 65, 2, -31, 0, 99, 2, 83, 782, 1}, {170, 45, 75, 90, 2, 24, -802, -66}}
+for aa as a do
+    print($"Before: \{{a:concat(", ")}}")
+    radix_sort(a)
+    print($"After : \{{a:concat(", ")}}")
+    print()
+end