14LongestCommonPrefix

public String longestCommonPrefix(String[] strs) {
if(strs == null || strs.length == 0){
return new String(); //guard clause
}

int minLen = strs[0].length();
int eleIndex = 0;
for(int i = 1; i < strs.length; i++){
if(strs[i].length() < minLen){
eleIndex = i;
minLen = strs[i].length();
}
}

String str = strs[eleIndex];
int index = minLen;
for(int i = 0; i < strs.length; i++){
for(int j = 0; j < index; j++){ //和第i个字符串比较前缀
if(str.charAt(j) != strs[i].charAt(j)){
index = j;
break;
}
}
}
return str.substring(0, index);
}