LongestCommonPrefix.java

/**
 * Longest Common Prefix http://oj.leetcode.com/problems/longest-common-prefix/
 * 
 * Write a function to find the longest common prefix string amongst an array of strings.
 * 
 * @author joshluo
 * 
 *         Really easy problem.
 */

public class LongestCommonPrefix {
    public String longestCommonPrefix(String[] strs) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        assert (strs != null);
        if (strs.length == 0)
            return "";
        String longest = strs[0];
        for (String str : strs) {
            int i = 0;
            while (i < Math.min(longest.length(), str.length())) {
                if (longest.charAt(i) != str.charAt(i))
                    break;
                i++;
            }
            longest = longest.substring(0, i);
        }
        return longest;
    }
}