First power of 2 that has leading decimal digits of 12: Difference between revisions

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 </pre>
+=={{header|Kotlin}}==
+{{trans|Java}}
+<lang scala>import kotlin.math.ln
+import kotlin.math.pow
+fun main() {
+    runTest(12, 1)
+    runTest(12, 2)
+    runTest(123, 45)
+    runTest(123, 12345)
+    runTest(123, 678910)
+}
+private fun runTest(l: Int, n: Int) {
+//    System.out.printf("p(%d, %d) = %,d%n", l, n, p(l, n))
+    println("p($l, $n) = %,d".format(p(l, n)))
+}
+fun p(l: Int, n: Int): Int {
+    var m = n
+    var test = 0
+    val log = ln(2.0) / ln(10.0)
+    var factor = 1
+    var loop = l
+    while (loop > 10) {
+        factor *= 10
+        loop /= 10
+    }
+    while (m > 0) {
+        test++
+        val value = (factor * 10.0.pow(test * log % 1)).toInt()
+        if (value == l) {
+            m--
+        }
+    }
+    return test
+}</lang>
+{{out}}
+<pre>p(12, 1) = 7
+p(12, 2) = 80
+p(123, 45) = 12,710
+p(123, 12345) = 3,510,491
+p(123, 678910) = 193,060,223</pre>
 =={{header|Pascal}}==