rohitnotes
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diff --git a/‎problems/src/string/ImplementStrStr.java‎
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@@ -137,6 +137,7 @@ My accepted leetcode solutions to some of the common interview problems.
 - [String to Integer](problems/src/string/StringToInteger.java) (Medium)
 - [Text Justification](problems/src/string/TextJustification.java) (Hard)
 - [ZigZag Conversion](problems/src/string/ZigZagConversion.java) (Medium)
+- [Implement StrStr](problems/src/string/ImplementStrStr.java) (Easy)
 
 
 #### [Tree](problems/src/tree)
 
@@ -0,0 +1,42 @@
+package string;
+
+/**
+ * Created by gouthamvidyapradhan on 24/06/2017.
+ * Implement strStr().
+
+ Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
+
+ Solution O(N ^ 2)
+ */
+public class ImplementStrStr {
+    public static void main(String[] args) throws Exception{
+        System.out.println(new ImplementStrStr().strStr("AABB", ""));
+    }
+
+    public int strStr(String haystack, String needle) {
+        if(haystack.isEmpty() && needle.isEmpty()) return 0;
+        if(needle.isEmpty()) return 0;
+        for(int i = 0, l = haystack.length(); i < l; i ++){
+            if(haystack.charAt(i) == needle.charAt(0)){
+                if(isEqual(haystack, needle, i))
+                    return i;
+            }
+        }
+        return -1;
+    }
+
+    private boolean isEqual(String haystack, String needle, int i){
+        int hL = haystack.length();
+        int nL = needle.length();
+        int j = 0;
+        while(i < hL && j < nL){
+            if(haystack.charAt(i) != needle.charAt(j))
+                return false;
+            i++;
+            j++;
+        }
+        return j >= nL;
+    }
+
+
+}