// 2180. Count Integers With Even Digit Sum #include "leetcode.h" /* * 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. */ class Solution { public: int countEven(int num) { int tmp = num, sum = 0; while (num > 0) { sum += num % 10; num /= 10; } return sum % 2 == 0 ? tmp / 2 : (tmp - 1) / 2; } }; int main() { Solution obj; printf("%d\n", obj.countEven(4)); // expect: 2 printf("%d\n", obj.countEven(30)); // expect: 14 }