leetcode

0 class Solution {

1 class Solution {

2 public:

3 string removeKdigits(string num, int k) {

4 if (num.length() <= k) return "0";

5 if (k == 0) return num;

6

7 string res = "";

8 stack<char> s;

9

10 s.push(num[0]);

11 for (int i = 1; i < num.length(); ++i) {

12 while (k > 0 && !s.empty() && num[i] < s.top()) {

13 --k;

14 s.pop();

15 }

16 s.push(num[i]);

17 if (s.size() == 1 && num[i] == '0') s.pop();

18 }

19

20 while (k && !s.empty())

21 --k, s.pop();

22

23 while (!s.empty())

24 res.push_back(s.top()), s.pop();

25

26 reverse(res.begin(), res.end());

27 return res.size() ? res : "0";

28 }

29 };