EASY/src/easy/ImplementStrStr.java

fishercoder1534 · fishercoder1534 · commit 95dbb95c0e87 · 2016-08-31T18:51:20.000-07:00
diff --git a/EASY/src/easy/ImplementStrStr.java b/EASY/src/easy/ImplementStrStr.java
@@ -0,0 +1,32 @@
+package easy;
+
+public class ImplementStrStr {
+/**You could use substring as follows, or use two pointers to go through the haystack, if substring API call is not allowed.*/
+    public static int strStr(String haystack, String needle) {
+        if(haystack == null || needle == null){
+            return -1;
+        }
+        if(haystack.isEmpty()){
+            return needle.isEmpty() ? 0 : -1;
+        }
+        if(needle.isEmpty()){
+            return 0;
+        }
+        for(int i = 0; i < haystack.length() - needle.length()+1; i++){
+            if(haystack.substring(i, i+needle.length()).equals(needle)) return i;
+        }
+        return -1;
+    }
+    
+    public static void main(String...args){
+//        String haystack = "a";
+//        String needle = "";
+        
+//        String haystack = "mississippi";
+//        String needle = "a";
+        
+        String haystack = "a";
+        String needle = "a";
+        strStr(haystack, needle);
+    }
+}
