unordered_map sometimes better than map:

got TLE with map on Collecting_Numbers_II.cpp but AC with unordered_map
-unordered is good for a lot of requests and a lot of data

CSES - CSES Problem Set/Collecting_Numbers.cpp

@@ -0,0 +1,19 @@
+//  Collecting Numbers
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+int main() {
+    int n; cin >> n;
+    vector<int> in(n);
+    for (auto &e: in) cin >> e;
+    int count = 1;
+    map<int, int> pos;
+    for (int i{}; i < n; i++) pos[in[i]] = i;
+    for (int i = 1; i < n; i++) {
+        if (pos[i] > pos[i+1]) count ++;
+    }
+    cout << count << endl;
+    return 0;
+}