2016 Update

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

@@ -0,0 +1,32 @@
+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)