Merge pull request #130 from roitt/longest-common-prefix

Longest common prefix

Author: blakeembrey

problems/longest-common-prefix/Readme.md

@@ -0,0 +1,13 @@
+# Longest Common Prefix
+
+Given a String array, find the longest common prefix.
+
+## Example
+
+```
+f([‘rocket’, ‘rockstar’, ‘rockbottom’, ‘rock’, ‘rollingstone’] // ‘ro’
+f([‘shuffle’, ‘shuttle’, ‘shut’] // ‘shu’
+```
+
+## Source
+Personal Phone Interview

solutions/java/LongestCommonPrefix.java

@@ -0,0 +1,20 @@
+public class LongestCommonPrefix {
+	public static void main(String[] args) {
+		LongestCommonPrefix lcs = new LongestCommonPrefix();
+		String[] input = { "rocket", "rockstar", "rockbottom", "rollingstone"};
+		System.out.println(lcs.getSubstring(input));
+	}
+
+	public String getSubstring(String[] input) {
+		String base = input[0];
+		for (int i = 0; i < base.length(); i++) {
+			for (int j = 1; j < input.length; j++) { // Run for all words
+				String comparer = input[j];
+				if (i >= comparer.length()
+						|| comparer.charAt(i) != base.charAt(i))
+					return base.substring(0, i);
+			}
+		}
+		return "";
+	}
+}