Update N-th Tribonacci Number.java

varunu28 · web-flow · commit 3a076706521d · 2021-09-24T11:57:43.000-05:00
diff --git a/Easy/N-th Tribonacci Number.java b/Easy/N-th Tribonacci Number.java
@@ -1,17 +1,10 @@
 class Solution {
   public int tribonacci(int n) {
-    int[] dp = new int[Math.max(n + 1, 3)];
-    dp[0] = 0;
-    dp[1] = 1;
-    dp[2] = 1;
-    return helper(n, dp);
-  }
-  
-  private int helper(int n, int[] dp) {
-    if (n == 0 || dp[n] != 0) {
-      return dp[n];
+    int[] arr = new int[38];
+    arr[1] = arr[2] = 1;
+    for (int i = 3; i < 38; i++) {
+      arr[i] = arr[i - 1] + arr[i - 2] + arr[i - 3];
     }
-    dp[n] = helper(n - 1, dp) + helper(n - 2, dp) + helper(n - 3, dp);
-    return dp[n];
+    return arr[n];
   }
 }
