Write a function to find the longest common prefix string amongst an array of strings.

Longest Common Prefix.cpp

class Solution {
public:
    string longestCommonPrefix(vector<string> &strs) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        string prefix = "";
        
        if(strs.size() == 0) {
            return prefix;
        }
        
        //get the next char from first line
        char cur;
        int index = 0;
        while(index < strs[0].length()) {
            cur = strs[0][index];
            for(int i = 0; i < strs.size(); ++i) {
                if(cur != strs[i][index]) {
                    return prefix;
                }
            }
            ++index;
            prefix += cur;
        }
        
        
        return prefix;
    }
};