multisets can be useful

CSES - CSES Problem Set/Concert_Tickets.cpp

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+//  Concert Tickets
+
+#include<bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+int main() {
+    int n, m; cin >> n >> m;
+    multiset<ll> price;
+    for (int i{}; i < n; i++) {ll a; cin >> a; price.insert(a);}
+    for (int i{}; i < m; i++) {
+        ll v; cin >> v;
+        auto it = price.upper_bound(v);
+        if (it == price.begin()) {
+            cout << -1 << endl;
+        } else {
+            cout << *(--it) << endl;
+            price.erase(it);
+        }
+    }
+    return 0;
+}