1 files changed, 4 insertions, 3 deletions

diff --git a/2024/09/day09a.cpp b/2024/09/day09a.cpp
index c52c8f0..80732d7 100644
--- a/2024/09/day09a.cpp
+++ b/2024/09/day09a.cpp
@@ -1,6 +1,7 @@
 #include <algorithm>
 #include <iostream>
 #include <map>
+#include <ranges>
 #include <set>
 #include <sstream>
 #include <string>
@@ -16,11 +17,11 @@ int main() {
                         a.push_back(id % 2 == 0 ? id/2 : -1); // -1 = space
 
         int j = 0;
-        for (int i = a.size()-1; i >= 0; i--) {
+        for (auto& x : a | views::reverse) {
                 while (a[j] >= 0) j++;
                 if (a[j] == -2) break;
-                a[j] = a[i];
-                a[i] = -2; // -2 = freed up
+                a[j] = x;
+                x = -2; // -2 = freed up
         }
 
         long long checksum = 0;