```
class Solution(object):
def removeKdigits(self, num, k):
"""
:type num: str
:type k: int
:rtype: str
"""
if k == len(num):
return "0"
if k == 0:
return num
n, i, digits, res = len(num), -1, 0, ""
while digits < n - k:
start = i + 1
cand = 10
for pos in range(start, k+digits+1):
if num[pos] == "0":
i = pos
cand = 0
# digits += 1
break
else:
if int(num[pos]) < cand:
cand = int(num[pos])
i = pos
res += str(cand)
digits += 1
return str(int(res))
```