Write a function to find the longest common prefix string amongst an array of strings.
class Solution { public: string longestCommonPrefix(vector<string> &strs) { // Start typing your C/C++ solution below // DO NOT write int main() function string result=""; if(strs.size() == 0) return result ; string first = strs[0] ; for(int i = 0; i < first.size() ;i++) { char c = first[i] ; for(int j =1 ; j< strs.size(); j++) if(i > strs[j].size() -1 || c != strs[j][i]) return result; result+=c; } return result ; } };