leetcode Longest Common Prefix

#include<iostream>
#include<string>
#include<vector>

using namespace std;


string longestCommonPrefix(vector<string> &strs) 
{
    
    int L = strs.size();
    if (L <1 )
    {
        return "";
    }
    string prefix = strs[0];
    for (int i = 1; i < L; i++)
    {
        int LPre = prefix.size();
        int LNow = strs[i].size();
        int LQ = LPre>LNow ? LNow : LPre;
        int j;
        for (j = 0; j < LQ; j++)
        {
            if (prefix[j] != strs[i][j])
                break;
        }
        if (j == LNow){
            prefix = strs[i];
        }
        else
        {
            prefix = strs[i].substr(0, j);
        }
    }
    return prefix;
}

int main()
{
    vector<string> strs = {"asdqwer","as","asdklj"};
    cout << longestCommonPrefix(strs) << endl;
}