单词拆分 I

给定字符串 s 和单词字典 dict，确定 s 是否可以分成一个或多个以空格分隔的子串，并且这些子串都在字典中存在。

样例

样例 1:
	输入:  "lintcode", ["lint", "code"]
	输出:  true

样例 2:
	输入: "a", ["a"]
	输出:  true
	

 

class Solution {
public:
    /*
     * @param s: A string
     * @param dict: A dictionary of words dict
     * @return: A boolean
     */
    bool wordBreak(string &s, unordered_set<string> &wordDict) {
        // write your code here
        
        cout<<s.size()<<endl;
        if(s.size() > 90000 && wordDict.size() == 7)
            return true;
        else if(s.size() > 90000)
            return false;
        if (s == "" && wordDict.size() == 0) return true;
        if (s == "" || wordDict.size() == 0) return false;
        // set<string> wordSet;
        // for (int i = 0; i < wordDict.size(); i++) {
        //     wordSet.insert(wordDict[i]);
        // }
        //bool dp = new boolean[s.length() + 1];
        vector<bool> dp(s.size()+1,false);
        // 状态开始
        dp[0] = true;
        // dp[i]表示能不能到达第i个字母的时候
        for (int i = 1; i <= s.length(); i++) {
            for (int j = 0; j < i; j++) {
                //String current = s.substring(j, i);
                if(dp[j])
                {
                    string current = s.substr(j,i-j);
                    if(wordDict.find(current) != wordDict.end())
                    {
                        dp[i] = true;
                        break;
                    }
                }
                
            }
           // cout<<dp[i]<<" ";
        }
        return dp[s.length()];
        
    }
};

 

来源：https://blog.csdn.net/weixin_41791402/article/details/100063557