leetcode Question 83: Restore IP Addresses

Restore IP Addresses:

Given a string containing only digits, restore it by returning all possible valid IP address combinations.

For example:

Given

"25525511135"

,

return

["255.255.11.135",
"255.255.111.35"]

. (Order does not matter)

Analysis:

This problem can be viewed as a DP problem. There needed 3 dots to divide the string, and make sure the IP address is valid:
less than or equal to 255, greater or equal to 0, and note that, "0X" or "00X" is not valid.

For the DP, the length of each part is from 1 to 3. We use a vector<string> to store each part, and cut the string every
time. Details see the code.

Note that "atoi" is for c-string, <string> need to convert to cstring by str.c_str();

Code(Updated 201309):

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Code(old version):

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