139 Word Break

Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.

For example, given
s = "leetcode",
dict = ["leet", "code"].

Return true because "leetcode" can be segmented as "leet code".

class Solution {
public:
    bool wordBreak(string s, unordered_set<string> &dict) {
        if (s.size()<=0 || dict.size()<=0)
            return false;
        vector<bool> res = vector<bool>(s.size(),false);
        
        if (dict.find(s.substr(0,1))!=dict.end())
            res[0]=true;
        for (int i=1;i<s.size();i++)
        {
            if (dict.find(s.substr(0,i+1))!=dict.end())
            {
                res[i]=true;
                continue;
            }
            for (int k=0;k<i;k++)
            {
                if (res[k]== true && dict.find(s.substr(k+1,i-k))!=dict.end())
                {
                    res[i]=true;
                    break;
                }
            }
        }
        return res[s.size()-1];
        
    }
};