chore: import upstream snapshot with attribution

dynamic_programming/fibonacci_bottom_up.cpp

@@ -0,0 +1,21 @@
+#include <iostream>
+using namespace std;
+int fib(int n) {
+    int res[3];
+    res[0] = 0;
+    res[1] = 1;
+    for (int i = 2; i <= n; i++) {
+        res[2] = res[1] + res[0];
+        res[0] = res[1];
+        res[1] = res[2];
+    }
+    return res[1];
+}
+int main() {
+    int n;
+    cout << "Enter n: ";
+    cin >> n;
+    cout << "Fibonacci number is ";
+    cout << fib(n) << endl;
+    return 0;
+}