// 2180. Count Integers With Even Digit Sum #include /* * given a positive integer 'num', return the number of positive integersless * than or equal to 'num' whose digit sums are event. the digitsum of a positive * integer is the sum of all of its digits. */ int countEven(int num) { int ans = 0; for (int i = 1; i <= num; i++) { int val = i, d = 0; while (val) { d += val % 10; val /= 10; } if (d % 2 == 0) ans++; } return ans; } int main() { printf("%d\n", countEven(4)); // expect: 2 printf("%d\n", countEven(30)); // expect: 14 }