斐波那契数列记忆化递归

others/test3-1.cpp

@@ -0,0 +1,22 @@
+// 斐波那契数列记忆化递归
+#include<bits/stdc++.h>
+using namespace std;
+using ll = long long;
+const ll p = 1e9 + 7;
+const int N = 1e5 + 3;
+ll dep[N]; 
+
+ll fib(int a){
+    if(a <= 2) return 1;
+    if(dep[a] != -1) return dep[a] % p;
+    return dep[a] = (fib(a-1) + fib(a-2)) % p;
+}
+int main(){
+    fill(dep, dep + N, -1);
+    int n; cin >> n;
+    cout << fib(n) << endl;
+    return 0;
+}
+/*
+1 1 2 3 5 8 13 21 34
+*/

others/test3.cpp

@@ -0,0 +1,21 @@
+// 斐波那契数列记忆化递归
+#include<bits/stdc++.h>
+using namespace std;
+#define int long long
+const int N = 1e5 + 3;
+int dep[N]; 
+
+int fib(int a){
+    if(a <= 2) return 1;
+    if(dep[a] != -1) return dep[a];
+    return dep[a] = fib(a-1) + fib(a-2);
+}
+signed main(){
+    fill(dep, dep + N, -1);
+    int n; cin >> n;
+    cout << fib(n) << endl;
+    return 0;
+}
+/*
+1 1 2 3 5 8 13 21 34
+*/