Digit Counts Jul 13, 2016 Count the number of occurrences of a digit, k, in numbers between 0 to n, inclusively. The digit k can be 0 to 9. Example Let n = 12, k = 1, then there are 5 digit 1 in the range from 0 to n: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12] class Solution { /* * param k : As description. * param n : As description. * return: An integer denote the count of digit k in 1..n */ public int digitCounts(int k, int n) { int res = 0; for (int i = 0; i <= n; i++) { res += count(k, i); } return res; } public int count(int k, int num) { if (k == 0 && num == 0) return 1; int res = 0; while (num > 0) { int r = num % 10; num /= 10; res += r == k ? 1 : 0; } return res; } }