Longest Common Prefix done

Author: rampatra

src/main/java/com/leetcode/strings/LongestCommonPrefix.java

@@ -0,0 +1,54 @@
+package com.leetcode.strings;
+
+/**
+ * Problem: https://leetcode.com/problems/longest-common-prefix/
+ *
+ * @author rampatra
+ * @since 2019-04-20
+ */
+public class LongestCommonPrefix {
+
+    /**
+     * Time complexity: O(r * c)
+     * where,
+     * r = no. of strings
+     * c = max. no. of characters in a particular string
+     * <p>
+     * Runtime: <a href="https://leetcode.com/submissions/detail/223735469/">1 ms</a>.
+     *
+     * @param strs
+     * @return
+     */
+    public static String longestCommonPrefix(String[] strs) {
+        StringBuilder sb = new StringBuilder();
+
+        int row;
+        for (int col = 0; col < Integer.MAX_VALUE; col++) {
+            for (row = 0; row < strs.length - 1; row++) {
+                // once we find a different character under one column, break the loop
+                if (col == strs[row].length()
+                        || col == strs[row + 1].length()
+                        || strs[row].charAt(col) != strs[row + 1].charAt(col)) {
+                    break;
+                }
+            }
+
+            // check the row counter to figure whether all characters in a particular column are identical
+            if (row == strs.length - 1 && strs[0].length() > 0 && col < strs[0].length()) {
+                sb.append(strs[0].charAt(col));
+            } else {
+                break;
+            }
+        }
+
+        return sb.toString();
+    }
+
+    public static void main(String[] args) {
+        System.out.println(longestCommonPrefix(new String[]{}));
+        System.out.println(longestCommonPrefix(new String[]{""}));
+        System.out.println(longestCommonPrefix(new String[]{"a"}));
+        System.out.println(longestCommonPrefix(new String[]{"flower", "flow", "flight"}));
+        System.out.println(longestCommonPrefix(new String[]{"dog", "racecar", "car"}));
+    }
+}