public class Solution {
    public string LongestCommonPrefix(string[] strs) {
		StringBuilder result = new StringBuilder();
		if (strs != null && strs.Length > 0) {
			Array.Sort(strs);
			char[] a = strs[0].ToCharArray();
			char[] b = strs[strs.Length - 1].ToCharArray();
			for (int i = 0; i < a.Length; i++) {
				if (b.Length > i && b[i] == a[i]) {
					result.Append(b[i]);
				} else {
					return result.ToString();
				}
			}
			return result.ToString();
		} else {
			return "";
		}
    }
}