## Monday, May 15, 2017

### Longest Common Prefix

Problem statement

Write a function to find the longest common prefix string among an array of strings

Example
```Input  : {"tommorow", "tommy", "tomandGerry", "tod"}
Output : "to"

Output : "pra"
```

### Solution

• Take the first string in the array of strings at let us assume that it is a prefix
• Take the second string and compare it with prev string to find the first occurrence .
strs[i].indexOf(pre)!=0
Note: If it finds the occurrence then it would return 0 else -1
• Iterate through the array of strings till we find the longest common prefix
```public static String get(String [] strs)
{
//Check if the string array is null or the length is zero
if (strs.length==0 || strs==null ) return "";

//Get the first string in the array of strings
String pre=strs;
int i=1;
//iterate till the end of the array
while(i <strs.length)
{
//We are taking the second string and comparing if ```
```                        //index of previous returns 0
//If it returns zero we know that its common prefix
while(strs[i].indexOf(pre)!=0)
pre=pre.substring(0, pre.length()-1);
i++;
}
return pre;
}
```