September 2017 Update

Task/Casting-out-nines/JavaScript/casting-out-nines-1.js

@@ -0,0 +1,47 @@
+function main(s, e, bs, pbs) {
+    bs = bs || 10;
+    pbs = pbs || 10
+    document.write('start:', toString(s), ' end:', toString(e),
+        ' base:', bs, ' printBase:', pbs)
+    document.write('<br>castOutNine: ');
+    castOutNine()
+    document.write('<br>kaprekar: ');
+    kaprekar()
+    document.write('<br><br>')
+
+    function castOutNine() {
+        for (var n = s, k = 0, bsm1 = bs - 1; n <= e; n += 1)
+            if (n % bsm1 == (n * n) % bsm1) k += 1,
+                document.write(toString(n), ' ')
+        document.write('<br>trying ', k, ' numbers instead of ', n = e - s + 1,
+            ' numbers saves ', (100 - k / n * 100)
+            .toFixed(3), '%')
+    }
+
+    function kaprekar() {
+        for (var n = s; n <= e; n += 1)
+            if (isKaprekar(n)) document.write(toString(n), ' ')
+
+        function isKaprekar(n) {
+            if (n < 1) return false
+            if (n == 1) return true
+            var s = (n * n)
+                .toString(bs)
+            for (var i = 1, e = s.length; i < e; i += 1) {
+                var a = parseInt(s.substr(0, i), bs)
+                var b = parseInt(s.substr(i), bs)
+                if (b && a + b == n) return true
+            }
+            return false
+        }
+    }
+
+    function toString(n) {
+        return n.toString(pbs)
+            .toUpperCase()
+    }
+}
+main(1, 10 * 10 - 1)
+main(1, 16 * 16 - 1, 16)
+main(1, 17 * 17 - 1, 17)
+main(parseInt('10', 17), parseInt('gg', 17), 17, 17)

Task/Casting-out-nines/JavaScript/casting-out-nines-2.js

@@ -0,0 +1,46 @@
+(() => {
+    'use strict';
+
+    // co9 :: Int -> Int
+    const co9 = n =>
+        n <= 8 ? n : co9(
+            digits(10, n)
+            .reduce((a, x) => x !== 9 ? a + x : a, 0)
+        );
+
+    // GENERIC FUNCTIONS
+
+    // digits :: Int -> Int -> [Int]
+    const digits = (base, n) => {
+        if (n < base) return [n];
+        const [q, r] = quotRem(n, base);
+        return [r].concat(digits(base, q));
+    };
+
+    // quotRem :: Integral a => a -> a -> (a, a)
+    const quotRem = (m, n) => [Math.floor(m / n), m % n];
+
+    // range :: Int -> Int -> [Int]
+    const range = (m, n) =>
+        Array.from({
+            length: Math.floor(n - m) + 1
+        }, (_, i) => m + i);
+
+    // squared :: Num a => a -> a
+    const squared = n => Math.pow(n, 2);
+
+    // show :: a -> String
+    const show = x => JSON.stringify(x, null, 2);
+
+    // TESTS
+    return show({
+        test1: co9(232345), //-> 1
+        test2: co9(34234234), //-> 7
+        test3: co9(232345 + 34234234) === co9(232345) + co9(34234234), //-> true
+        test4: co9(232345 * 34234234) === co9(232345) * co9(34234234), //-> true,
+        task2: range(1, 100)
+            .filter(n => co9(n) === co9(squared(n))),
+        task3: (k => range(1, 100)
+            .filter(n => (n % k) === (squared(n) % k)))(16)
+    });
+})();

Task/Casting-out-nines/JavaScript/casting-out-nines.js

@@ -1,32 +0,0 @@
-function main( s, e, bs, pbs ) {
-	bs = bs || 10; pbs = pbs || 10
-	document.write('start:',toString(s), ' end:',toString(e), ' base:',bs, ' printBase:',pbs )
-	document.write('<br>castOutNine: '); castOutNine()
-	document.write('<br>kaprekar: '); kaprekar()
-	document.write('<br><br>')
-	function castOutNine() {
-		for (var n=s, k=0, bsm1=bs-1; n<=e; n+=1) if (n%bsm1 == (n*n)%bsm1) k+=1, document.write(toString(n), ' ')
-		document.write('<br>trying ', k, ' numbers instead of ', n=e-s+1, ' numbers saves ',  (100-k/n*100).toFixed(3), '%')
-	}
-	function kaprekar() {
-		for (var n=s; n<=e; n+=1) if (isKaprekar(n)) document.write(toString(n), ' ')
-		function isKaprekar( n ) {
-			if ( n < 1 ) return false
-			if ( n == 1 ) return true
-			var s = (n * n).toString(bs)
-			for (var i=1, e=s.length; i<e; i+=1) {
-				var a = parseInt(s.substr(0, i), bs)
-				var b = parseInt(s.substr(i), bs)
-				if (b && a + b == n) return true
-		    }
-		    return false
-		}
-	}
-	function toString( n ) {
-		return n.toString(pbs).toUpperCase()
-	}
-}
-main(1, 10*10-1)
-main(1, 16*16-1, 16)
-main(1, 17*17-1, 17)
-main(parseInt('10',17), parseInt('gg',17), 17, 17)