CSES - Shared codeLink to this code:
https://cses.fi/paste/4bd65da956041662b55493/
#include<bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<class T> using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define int long long
const int infinity = 1e15;
const int N = 4 * (1e5 +1);
int arr[N];
void solve(){
int n, q, a, b;
char ch;
cin >> n >> q;
oset<pair<int,int>> s;
for(int i=1;i<=n;i++) {
cin >> arr[i];
s.insert({arr[i], i});
}
while(q--) {
cin >> ch >> a >> b;
if(ch == '?') {
int n1 = s.order_of_key({a-1, infinity});
int n2 = s.order_of_key({b, infinity});
cout << n2-n1 << "\n";
} else {
s.erase({arr[a], a});
arr[a] = b;
s.insert({arr[a], a});
}
}
}
#undef int
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int t=1;
//cin >> t;
while(t--){
solve();
}
return 0;
}