原题链接: https://oj.leetcode.com/problems/longest-common-prefix/

public String longestCommonPrefix(String[] strs) {
    if (strs == null) return null;
    if (strs.length == 0) return "";

    String shortestStr = null;

    // find the shortest string element
    for (int i = 0, s = strs.length; i < s; i++) {
        if (shortestStr == null) {
            shortestStr = strs[i];
        } else if (strs[i].length() < shortestStr.length()) {
            shortestStr = strs[i];
        }
    }

    StringBuilder longestCommonPrefix = new StringBuilder("");
    int shortestStrLen = shortestStr.length();
    char c;
    boolean quitMatch = false;

    for (int i = 0; i < shortestStrLen; i++) {
        c = shortestStr.charAt(i);

        for (int j = 0, s = strs.length; j < s; j++) {
            if (strs[j].charAt(i) != c) {
                quitMatch = true;
                break;
            }

            if (j == strs.length - 1) {
                longestCommonPrefix.append(c);
            }
        }

        if (quitMatch) break;
    }

    return longestCommonPrefix.toString();
}