Data commit

Task/Heronian-triangles/CoffeeScript/heronian-triangles.coffee

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+heronArea = (a, b, c) ->
+    s = (a + b + c) / 2
+    Math.sqrt s * (s - a) * (s - b) * (s - c)
+
+isHeron = (h) -> h % 1 == 0 and h > 0
+
+gcd = (a, b) ->
+    leftover = 1
+    dividend = if a > b then a else b
+    divisor = if a > b then b else a
+    until leftover == 0
+        leftover = dividend % divisor
+        if leftover > 0
+            dividend = divisor
+            divisor = leftover
+    divisor
+
+list = []
+for c in [1..200]
+    for b in [1..c]
+        for a in [1..b]
+            area = heronArea(a, b, c)
+            if gcd(gcd(a, b), c) == 1 and isHeron(area)
+                list.push new Array(a, b, c, a + b + c, area)
+
+sort = (list) ->
+    swapped = true
+    while swapped
+        swapped = false
+        for i in [1..list.length-1]
+            if list[i][4] < list[i - 1][4] or list[i][4] == list[i - 1][4] and list[i][3] < list[i - 1][3]
+                temp = list[i]
+                list[i] = list[i - 1]
+                list[i - 1] = temp
+                swapped = true
+sort list
+
+# some results:
+console.log 'primitive Heronian triangles with sides up to 200: ' + list.length
+console.log 'First ten when ordered by increasing area, then perimeter:'
+for i in list[0..10-1]
+    console.log  i[0..2].join(' x ') + ', p = ' + i[3] + ', a = ' + i[4]
+
+console.log '\nHeronian triangles with area = 210:'
+for i in list
+    if i[4] == 210
+        console.log i[0..2].join(' x ') + ', p = ' + i[3]