q1=>longest string chain

int longestStrChain(vector<string>& words) {
      sort(words.begin(),words.end(),[](string a,string b){return a.length()<b.length();});
        int sum=0;
        map<string,int>dp;
        int i,j;

        for(string s:words)
        {
            for(i=0;i<s.length();i++)
            {
                dp[s]=max(1+dp[s.substr(0,i)+s.substr(i+1)],dp[s]);
            }
            sum=max(sum,dp[s]);
        }
        return sum;
    }