class Solution {
    public String longestCommonPrefix(String[] strs) {
        int n = strs.length;
        if(n==0){
            return "";
        }
        String prefix = strs[0];
        for(int i=1; i<n; i++){
            while(strs[i].indexOf(prefix)!=0){
                prefix = prefix.substring(0, prefix.length()-1);
                if(prefix.length()==0)
                    return "";
            }
        }
        return prefix;
    }
}