Algo_LongestCommonPrefix.java

/*
    Longest Common Prefix

    Example 1:
    Input: strs = ["flower","flow","flight"]
    Output: "fl"

    Example 2:
    Input: strs = ["dog","racecar","car"]
    Output: ""
    Explanation: There is no common prefix among the input strings.
 */
public class Algo_LongestCommonPrefix {

    public String longestCommonPrefix(String[] strs) {
        StringBuilder result = new StringBuilder();
        String firstString = strs[0];
        int charIndex = 0;
        for (char currentChar : firstString.toCharArray()) {
            for (int stringIndex = 1; stringIndex < strs.length; stringIndex++) {
                char c1 = strs[stringIndex].charAt(charIndex);
                if (c1 != currentChar) {
                    return result.toString();
                }
            }
            result.append(currentChar);
            charIndex++;
        }
        return result.toString();
    }

    public static void main(String[] args) {
        String[] strs = {"flower","flow","flight"};
        String[] strs2 = {"dog","racecar","car"};

        Solution s1 = new Solution();
        System.out.println(s1.longestCommonPrefix(strs));
        System.out.println(s1.longestCommonPrefix(strs2));
    }
}