[leetcode]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)

深度优先搜索吧。注意剪枝的简单条件。还有注意ip的规则！

class Solution {
public:
    vector<string> restoreIpAddresses(string s) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<string> *v = new vector<string>();
        int * array = new int[4];
        DepthFirst(0,s.length()-1,0,array,s,v);
        return *v;
    }
    void DepthFirst(int l,int r,int depth,int *array,string source,vector<string> *v)
    {
        if(depth == 4)
        {
            int l0 = 0,l1 = array[0],l2 = array[1]+array[0],l3 = array[2] + array[1] + array[0];
            string s = source.substr(l0,array[0]) + "." + source.substr(l1,array[1]) + 
             "." + source.substr(l2,array[2]) + "." + source.substr(l3,array[3]);
             v->push_back(s);
             return;
        }
        for(int i = 1;i <= 3;i++)
        {
            if(r - l - i + 1 < 3 - depth)
                continue;
            if(r - l - i + 1 > 3 * (3 - depth))
                continue;
            if(i > 1)
            {
                if(source.at(l) == '0')
                    continue;
            }
            int num = 0;
            int pow[3] = {1,10,100};
            for(int j = i; j >= 1; j--)
            {
                num += (source.at(l + j - 1) - '0')*pow[i - j];
            }
            if(num > 255)
                continue;
            array[depth] = i;
            DepthFirst(l+i,r,depth+1,array,source,v);
        }
    }
};