题目：

题解：

#define MIN(x, y) ((x) < (y) ? (x) : (y))

int getSteps(int curr, long n) {
    int steps = 0;
    long first = curr;
    long last = curr;
    while (first <= n) {
        steps += MIN(last, n) - first + 1;
        first = first * 10;
        last = last * 10 + 9;
    }
    return steps;
}

int findKthNumber(int n, int k) {
    int curr = 1;
    k--;
    while (k > 0) {
        int steps = getSteps(curr, n);
        if (steps <= k) {
            k -= steps;
            curr++;
        } else {
            curr = curr*10;
            k--;
        }
    }
    return curr;
}