Submission

PPPPPPPPPPPPPPPPPPPP

Score: 100

User: njoop

Problemset: สุ่มสลับ

Language: cpp

Time: 0.006 second

Submitted On: 2024-11-28 23:59:41

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
#define ll long long
 
using namespace __gnu_pbds;
using namespace std;
 
int n, in, ord[300010], idx;
ll fac[300010], mod = 1e9+7, ans;
vector<pair<int, int>> v;
string s2;
 
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
 
ordered_set s;

int main() {
    cin.tie(0)->sync_with_stdio(0);
    fac[0] = 1;
    for(int i=1; i<300010; i++) {
        fac[i] = i*fac[i-1];
        fac[i] %= mod;
    }
    cin >> n;
    cin >> s2;
    for(int i=0; i<n; i++) {
        v.push_back({int(s2[i]-'A'+1), i+1});
    }
    sort(v.begin(), v.end());
    for(int i=0; i<v.size(); i++) {
        ord[v[i].second] = i;
    }
    for(int i=1; i<=n; i++) {
        idx = s.order_of_key(ord[i]);
        ans += ((ord[i]-idx)*fac[n-i])%mod;
        ans %= mod;
        s.insert(ord[i]);
    }
    cout << (ans+1)%mod;
    return 0;
}