Data commit

Task/Increasing-gaps-between-consecutive-Niven-numbers/C/increasing-gaps-between-consecutive-niven-numbers.c

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+#include <locale.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+
+// Returns the sum of the digits of n given the
+// sum of the digits of n - 1
+uint64_t digit_sum(uint64_t n, uint64_t sum) {
+    ++sum;
+    while (n > 0 && n % 10 == 0) {
+        sum -= 9;
+        n /= 10;
+    }
+    return sum;
+}
+
+inline bool divisible(uint64_t n, uint64_t d) {
+    if ((d & 1) == 0 && (n & 1) == 1)
+        return false;
+    return n % d == 0;
+}
+
+int main() {
+    setlocale(LC_ALL, "");
+
+    uint64_t previous = 1, gap = 0, sum = 0;
+    int niven_index = 0, gap_index = 1;
+
+    printf("Gap index  Gap    Niven index    Niven number\n");
+    for (uint64_t niven = 1; gap_index <= 32; ++niven) {
+        sum = digit_sum(niven, sum);
+        if (divisible(niven, sum)) {
+            if (niven > previous + gap) {
+                gap = niven - previous;
+                printf("%'9d %'4llu %'14d %'15llu\n", gap_index++,
+                       gap, niven_index, previous);
+            }
+            previous = niven;
+            ++niven_index;
+        }
+    }
+    return 0;
+}