refactor 509

fishercoder1534 · fishercoder1534 · commit 63393f2c11f7 · 2020-07-15T09:02:35.000-07:00
diff --git a/src/main/java/com/fishercoder/solutions/_509.java b/src/main/java/com/fishercoder/solutions/_509.java
@@ -3,87 +3,59 @@
 import java.util.ArrayList;
 import java.util.List;
 
-/**
- * 509. Fibonacci Number
- *
- * The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence,
- * such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,
- *
- * F(0) = 0,   F(1) = 1
- * F(N) = F(N - 1) + F(N - 2), for N > 1.
- * Given N, calculate F(N).
- *
- * Example 1:
- * Input: 2
- * Output: 1
- * Explanation: F(2) = F(1) + F(0) = 1 + 0 = 1.
- *
- * Example 2:
- * Input: 3
- * Output: 2
- * Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.
- *
- * Example 3:
- * Input: 4
- * Output: 3
- * Explanation: F(4) = F(3) + F(2) = 2 + 1 = 3.
- *
- * Note:
- * 0 ≤ N ≤ 30.
- */
 public class _509 {
-  public static class Solution1 {
-    /**
-     * Time: O(n)
-     * Space: O(n)
-     */
-    public int fib(int N) {
-      List<Integer> list = new ArrayList<>();
-      list.add(0);
-      list.add(1);
-      for (int i = 2; i <= N; i++) {
-        list.add(list.get(i - 1) + list.get(i - 2));
-      }
-      return list.get(N);
+    public static class Solution1 {
+        /**
+         * Time: O(n)
+         * Space: O(n)
+         */
+        public int fib(int N) {
+            List<Integer> list = new ArrayList<>();
+            list.add(0);
+            list.add(1);
+            for (int i = 2; i <= N; i++) {
+                list.add(list.get(i - 1) + list.get(i - 2));
+            }
+            return list.get(N);
+        }
     }
-  }
 
-  public static class Solution2 {
-    /**
-     * Time: O(n)
-     * Space: O(n)
-     */
-    public int fib(int N) {
-      if (N < 2) {
-        return N;
-      }
-      int[] fibNums = new int[N + 1];
-      fibNums[0] = 0;
-      fibNums[1] = 1;
-      for (int i = 2; i <= N; i++) {
-        fibNums[i] = fibNums[i - 1] + fibNums[i - 2];
-      }
-      return fibNums[N];
+    public static class Solution2 {
+        /**
+         * Time: O(n)
+         * Space: O(n)
+         */
+        public int fib(int N) {
+            if (N < 2) {
+                return N;
+            }
+            int[] fibNums = new int[N + 1];
+            fibNums[0] = 0;
+            fibNums[1] = 1;
+            for (int i = 2; i <= N; i++) {
+                fibNums[i] = fibNums[i - 1] + fibNums[i - 2];
+            }
+            return fibNums[N];
+        }
     }
-  }
 
-  public static class Solution3 {
-    /**
-     * Time: O(n)
-     * Space: O(1)
-     */
-    public int fib(int N) {
-      if (N < 2) {
-        return N;
-      }
-      int a = 0;
-      int b = 1;
-      while (N-- > 1) {
-        int sum = a + b;
-        a = b;
-        b = sum;
-      }
-      return b;
+    public static class Solution3 {
+        /**
+         * Time: O(n)
+         * Space: O(1)
+         */
+        public int fib(int N) {
+            if (N < 2) {
+                return N;
+            }
+            int a = 0;
+            int b = 1;
+            while (N-- > 1) {
+                int sum = a + b;
+                a = b;
+                b = sum;
+            }
+            return b;
+        }
     }
-  }
 }
