feat: BigInt fib

Author: sl1673495

动态规划/斐波那契数列-509.js

@@ -3,14 +3,41 @@
  * @return {number}
  */
 let fib = function (N) {
-  let dp = new Array(N + 1).fill(0);
+  let dp = []
 
-  dp[0] = 0;
-  dp[1] = 1;
+  dp[0] = 0n;
+  dp[1] = 1n;
 
   for (let i = 2; i <= N; i++) {
     dp[i] = dp[i - 1] + dp[i - 2];
   }
 
   return dp[N];
 };
+
+// let fib = (function () {
+//   let memo = new Map();
+//   return function (n) {
+//     // 优先从记忆里取 找到就直接 return
+//     // 否则又要进入下面的递归逻辑 非常耗时
+//     let memorized = memo.get(n);
+//     if (memorized) {
+//       return memorized;
+//     }
+
+//     if (n == 1 || n == 2) {
+//       return 1;
+//     }
+
+//     let f1 = fib(n - 1)
+//     let f2 = fib(n - 2)
+
+//     // 记忆下来
+//     memo.set(n - 1, f1)
+//     memo.set(n - 2, f2)
+
+//     return f1 + f2
+//   };
+// })();
+
+console.log(fib(10000));