3. Digit Counts【medium】

Count the number of k's between 0 and n. k can be 0 - 9.

 

Example

if n = 12, k = 1 in

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]

we have FIVE 1's (1, 10, 11, 12)

解法一：

class Solution {
 public:
    // param k : description of k
    // param n : description of n
    // return ans a integer
    int digitCounts(int k, int n) {
        int count = 0;
        if (k == 0) {
            count = 1;
        }
        for (int i = 1; i <= n; i++) {
            int number = i;
            while (number > 0) {
                if (number % 10 == k) {
                    count += 1;
                } 
                number /= 10;
            }
        }
        
        return count;
    }
};