剑指 Offer 10- I. 斐波那契数列.

lib/leetcode_1_fib.js

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+// 剑指 Offer 10- I. 斐波那契数列. 
+// https://leetcode-cn.com/problems/fei-bo-na-qi-shu-lie-lcof/
+// start  21:45    end  
+
+/**
+ * @param {number} n
+ * @return {number}
+ */
+var fib = function (n) {
+    let res = [0, 1]
+
+    function f(n) {
+        if (typeof res[n] !== 'undefined') {
+            return res[n]
+        }
+        // console.log(`res[${n}] = f(${n - 1}) + f(${n - 2})`)
+        res[n] = (f(n - 1) + f(n - 2)) % 1000000007
+        // console.log(res)
+        return res[n]
+    }
+    return f(n)
+};
+
+console.log(fib(81))