lintcode-medium-Digit Counts

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) {
// write your code here

int count = 0;

for(int i = k ; i <= n; i++){
count += singleCount(i, k);
}

return count;
}

public int singleCount(int num, int k){
if(num == 0 && k == 0)
return 1;

int count = 0;

while(num > 0){
if(num % 10 == k)
count++;

num /= 10;
}

return count;
}

};