Question:
Longest Common Prefix
Write a function to find the longest common prefix string amongst an array of strings.
If there is no common prefix, return an empty string "".
Example 1:
Input: ["flower","flow","flight"]
Output: "fl"Example 2:
Input: ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.
Note:
All given inputs are in lowercase letters a-z.
My solution is thinking:
Comparison of a first and second i-alphabet characters, if the first letter of the i-th and the second character the same, the second and third i th letter, if equal, letters will be added to the i-th final str, the size of i is from 0 until the last cycle.
The problem is:
class Solution {
public String longestCommonPrefix(String[] strs) {
int Strslength = strs.length;
if(Strslength>1)
{
int minLength = strs[0].length();
//O(n)
for(String str:strs)
{
int strLength = str.length();
if(minLength > strLength)
{
minLength = strLength;
}
}
//Store output ;
String str = "";
label:for(int i=0;i<minLength;i++)
{
for(int j=1;j<strs.length;j++)
{
if((strs[j-1].charAt(i))!=(strs[j].charAt(i)))
{
break label;
}
}
str+= strs[0].charAt(i);
}
return str;
}
else if(Strslength==1)
{
return strs[0];
}
else
{
return "";
}
}
}
Others solution:
In this solution, the authors found that mainly through two string values are equal, and then returns the result as a string and continue to look for use indexOf function, first find an equal position.
public static String longestCommonPrefix(String[] strs) {
if(strs.length==0){return "";}
String prefix = strs[0];
for(int i=1;i<strs.length;i++)
{
while (strs[i].indexOf(prefix)!=0)
{
prefix= prefix.substring(0,prefix.length()-1);
}
}
return prefix;
}