'commit'

TangDou/CSP-J/AcWingTraining/T6/432.cpp

@@ -0,0 +1,35 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+const int N = 100010;
+
+// 加法高精度
+int a[N], b[N];
+int al, bl;
+void add(int a[], int &al, int b[], int &bl) {
+    int t = 0;
+    al = max(al, bl);
+    for (int i = 1; i <= al; i++) {
+        t += a[i] + b[i];
+        a[i] = t % 10;
+        t /= 10;
+    }
+    if (t) a[++al] = 1;
+}
+
+int main() {
+    int n;
+    cin >> n;
+    b[++bl] = 1;
+
+    for (int i = 1; i <= n; i++) {
+        add(a, al, a, al);
+        add(a, al, b, bl);
+    }
+
+    // 最后再乘以2
+    add(a, al, a, al);
+
+    for (int i = al; i; i--) cout << a[i];
+    return 0;
+}