compute power

Recursion/Power.java

@@ -0,0 +1,39 @@
+import java.beans.PropertyEditorSupport;
+
+public class Power{
+        // 0(k)
+    public static int powerRec(int n , int k) {
+        if(k == 0) return 1;
+        return n*powerRec(n, k-1);
+    }
+
+    public static int powerIter(int n , int k) {
+         int result = 1;
+        for(int i = 1; i <= k; i++)
+            result*=n;
+      return result;
+    }
+
+    //o(logk)  t(k/2) +1 , t(k/4) + 2,  t(k/2^i)+ i == logk like binary search
+    public static int powerRecEf(int n , int k) {
+        if(k == 0) return 1;
+        if(k % 2 != 0) {
+            int result =  n*powerRecEf(n,k-1);
+            return result;
+        } else {
+            int result = powerRecEf(n, k / 2);
+            return result * result;
+        }
+    }
+
+
+
+
+    public static void main(String[] args) {
+            System.out.println(powerRec(2,3));
+            System.out.println(powerIter(2 ,5));
+            System.out.println(powerRecEf(2 ,6));
+        }
+
+
+}