Longest Common Prefix

class Solution {
public:
string longestCommonPrefix(vector<string>& strs) {

if (strs.size() == 0)   //数组长度为0，返回空
return "";

string preStr = strs[0];
for (int i = 1;i < strs.size(); i++){
if(preStr.length() == 0 || strs[i].length() == 0){
return "";
}

int j = 0;
string tempStr = "";
while(j<preStr.length() && j<strs[i].length()){
if(preStr[j] == strs[i][j]){
tempStr += preStr[j];
j++;
}else{
break;
}
}
preStr = tempStr;
}
return preStr;
}
};