Increasing gaps between consecutive Niven numbers: Difference between revisions

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@@ Line 116: / Line 116: @@
 // Returns the sum of the digits of n given the
 // sum of the digits of n - 1
-uint64_t digit_sum(uint64_t n, int sum)
+uint64_t digit_sum(uint64_t n, int sum) {
-{
     ++sum;
-    while (n > 0 && n % 10 == 0)
+    while (n > 0 && n % 10 == 0) {
-    {
         sum -= 9;
         n /= 10;
@@ Line 127: / Line 125: @@
 }
+inline bool divisible(uint64_t n, uint64_t d) {
-int main()
+    if ((d & 1) == 0 && (n & 1) == 1)
-{
+        return false;
+    return n % d == 0;
+}
+int main() {
     // Print numbers with commas
     std::cout.imbue(std::locale(""));
@@ Line 136: / Line 139: @@
     std::cout << "Gap index  Gap    Niven index    Niven number\n";
-    for (uint64_t niven = 1; gap_index <= 32; ++niven)
+    for (uint64_t niven = 1; gap_index <= 32; ++niven) {
-    {
         sum = digit_sum(niven, sum);
-        if (niven % sum == 0)
+        if (divisible(niven, sum)) {
-        {
+            if (niven > previous + gap) {
-            if (niven > previous + gap)
-            {
                 gap = niven - previous;
                 std::cout << std::setw(9) << gap_index++