Use reference_wrapper in compress_coords

Author: adamant-pwn

cp-algo/util/compress_coords.hpp

@@ -3,19 +3,19 @@
 #include <algorithm>
 #include <vector>
 namespace cp_algo {
+    // coords is a range of reference_wrapper<T>
     std::vector<int> compress_coords(auto &coords) {
-        static_assert(std::is_pointer_v<std::ranges::range_value_t<decltype(coords)>>);
         std::vector<int> original;
         original.reserve(size(coords));
-        std::ranges::sort(coords, {}, [](int* x) {return *x;});
+        std::ranges::sort(coords);
         int idx = -1, prev = -1;
-        for(auto x: coords) {
-            if(*x != prev) {
+        for(auto &x: coords) {
+            if(x != prev) {
                 idx++;
-                prev = *x;
-                original.push_back(*x);
+                prev = x;
+                original.push_back(x);
             }
-            *x = idx;
+            x.get() = idx;
         }
         return original;
     }

verify/structures/fenwick/ordered_set.test.cpp

@@ -12,16 +12,16 @@ void solve() {
     int n, q;
     cin >> n >> q;
     vector a(n, 0);
-    vector<int*> coords;
+    vector<reference_wrapper<int>> coords;
     for(auto &it: a) {
         cin >> it;
-        coords.push_back(&it);
+        coords.push_back(ref(it));
     }
     vector queries(q, pair{0, 0});
     for(auto &[t, x]: queries) {
         cin >> t >> x;
         if(t != 2) {
-            coords.push_back(&x);
+            coords.push_back(ref(x));
         }
     }
     auto values = cp_algo::compress_coords(coords);