Longest Common Prefix

longestCommonPrefix.java

/*
Write a function to find the longest common prefix string amongst an array of strings.

Algorithm:
1. Traverse through all the str inside strs and keep track of the longest
common prefix.
2. Make sure the lenght of the string does not exceed the length of str.
*/
public class Solution {
    public String longestCommonPrefix(String[] strs) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(strs.length == 0) return "";
        StringBuffer sb = new StringBuffer();
        int start = 0;
        while(true) {
            if(start == strs[0].length()) return sb.toString();
            char cur = strs[0].charAt(start);
            for(int i = 1; i < strs.length; i++) {
                if(start == strs[i].length()) return sb.toString();
                if(cur != strs[i].charAt(start)) return sb.toString();
            }
            sb.append(cur);
            start++;
        }
    }
}