'commit'

TangDou/AcWing/DP/GunDongShuZhu_ShangTaiJie_2.cpp

@@ -0,0 +1,23 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+//用例：
+/*
+20
+
+输出：
+10946
+*/
+int f[3];
+int n;
+int solve() {
+    f[0] = 1, f[1] = 2;
+    for (int i = 2; i < n; i++)
+        f[i % 3] = f[(i - 1) % 3] + f[(i - 2) % 3];
+    return f[(n - 1) % 3];
+}
+int main() {
+    scanf("%d", &n);
+    printf("%d\n", solve());
+    return 0;
+}