complete jungol//2194.cpp and fix it

storage/jungol/cpp/completed/3521.cpp

@@ -0,0 +1,47 @@
+#include <algorithm>
+#include <iostream>
+#include <vector>
+#include <cstdint>
+
+#define let auto
+#define fn auto
+#define usize size_t
+#define u64 uint64_t
+using namespace std;
+
+fn fastio() {
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+}
+
+fn main() -> int {
+    fastio();
+
+    let grams = vector<u64>{1, 2, 4, 8, 16};
+    let counts = vector<u64>(5);
+
+    for (usize i = 0; i < 5; i++) {
+        cin >> counts[i];
+    }
+
+    usize n;
+    cin >> n;
+
+    let usage = 0;
+    let i = 4;
+    while (i >= 0 && n > 0) {
+        if (counts[i] > 0 && n >= grams[i]) {
+            n -= grams[i];
+            counts[i] -= 1;
+            usage += 1;
+        } else {
+            i--;
+        }
+    }
+
+    if (n != 0) {
+        cout << "impossible" << endl;
+    } else {
+        cout << usage << endl;
+    }
+}