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-rw-r--r--add_digits.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/add_digits.c b/add_digits.c
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+++ b/add_digits.c
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+// 258. Add Digits
+#include <stdio.h>
+
+// given an integer 'num', repeatedly add all its digits until
+// the result has onlye one digit and return it
+
+int addDigits(int num) {
+ int sum = 0;
+ while (num) {
+ sum += num % 10;
+ num /= 10;
+ }
+ if (sum < 10)
+ return sum;
+ else
+ return addDigits(sum);
+}
+
+int main() {
+ printf("%d\n", addDigits(38)); // expect: 2
+ printf("%d\n", addDigits(0)); // expect: 0
+}