Add LeetCode 14. Longest Common Prefix java solution

Author: Tahanima

Algorithms/Easy/14_LongestCommonPrefix/Solution.java

@@ -0,0 +1,37 @@
+class Solution {
+    public static boolean isCommonForLength(int size, String[] strs) {
+        String substr = "";
+        
+        for (String s: strs) {
+            if (s.length() < size) {
+                return false;
+            }
+            
+            if (substr.equals("")) {
+                substr = s.substring(0, size);
+            } else {
+                if (!substr.equals(s.substring(0, size))) {
+                    return false;
+                }
+            }
+        }
+        
+        return true;
+    }
+    
+    public String longestCommonPrefix(String[] strs) {
+        int lo = 0, hi = 201, mid = 0;
+        
+        for (int iter = 0; iter <= 8; iter++) {
+            mid = (lo + hi) / 2;
+            
+            if (isCommonForLength(mid, strs)) {
+                lo = mid;
+            } else {
+                hi = mid;
+            }
+        }
+        
+        return mid > 0 ? strs[0].substring(0, mid): ""; 
+    }
+}