#include "bits/stdc++.h"
using namespace std;
#define int long long
const int MAXN = 3e5 + 10;
const int MOD = 1e9 + 7;
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
int bm(int b, int p) {
if(p==0) return 1 % MOD;
int r = bm(b, p >> 1);
if(p&1) return (((r*r) % MOD) * b) % MOD;
return (r*r) % MOD;
}
int inv(int b) {
return bm(b, MOD-2);
}
int fastlog(int x) {
return (x == 0 ? -1 : 64 - __builtin_clzll(x) - 1);
}
void printcase(int i) { cout << "Case #" << i << ": "; }
int bit[MAXN];
void add(int x, int v) {
for(;x<MAXN;x+=x&-x) bit[x] += v;
}
int sum(int x) {
int s = 0;
for(;x;x-=x&-x) s += bit[x];
return s;
}
void solve(int tc) {
int n;
cin>>n;
string s;
cin>>s;
int freq[2][26];
for(int i=0;i<2;i++)for(int j=0;j<26;j++)freq[i][j]=0;
for(int i=0;i<n;i++)freq[0][s[i]-'a']++;
for(int i=n;i<2*n;i++)freq[1][s[i]-'a']++;
int ans=0;
int cnt[2]={0,0};
bool move[2*n];
for(int i=0;i<2*n;i++)move[i]=0;
for(int i=n-1;i>=0;i--){
if(freq[0][s[i]-'a']>freq[1][s[i]-'a']) {
move[i]=1;
freq[0][s[i]-'a']--;
freq[1][s[i]-'a']++;
cnt[0]++;
ans+=n-1-i;
}
}
for(int i=n;i<2*n;i++){
if(freq[1][s[i]-'a']>freq[0][s[i]-'a']) {
move[i]=1;
freq[1][s[i]-'a']--;
freq[0][s[i]-'a']++;
cnt[1]++;
ans+=i-n;
}
}
ans+=cnt[0]*cnt[1];
string t;
for(int i=0;i<n;i++) if(!move[i]) t+=s[i];
for(int i=n;i<2*n;i++) if(move[i]) t+=s[i];
for(int i=0;i<n;i++) if(move[i]) t+=s[i];
for(int i=n;i<2*n;i++) if(!move[i]) t+=s[i];
s=t;
int a[n];
queue<int>id[26];
for(int i=0;i<n;i++){
id[s[i]-'a'].push(i);
}
for(int i=0;i<n;i++) {
a[i] = id[s[i+n]-'a'].front() + 1;
id[s[i+n]-'a'].pop();
ans += sum(n) - sum(a[i]);
add(a[i], 1);
}
cout << ans << "\n";
}
int32_t main() {
ios::sync_with_stdio(0); cin.tie(0);
int t = 1; //cin >> t;
for(int i=1; i<=t; i++) solve(i);
}
// 勿忘初衷
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
340 KB |
Output is correct |
2 |
Incorrect |
3 ms |
1364 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
340 KB |
Output is correct |
2 |
Incorrect |
3 ms |
1364 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
340 KB |
Output is correct |
2 |
Incorrect |
3 ms |
1364 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
340 KB |
Output is correct |
2 |
Incorrect |
1 ms |
340 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
340 KB |
Output is correct |
2 |
Incorrect |
3 ms |
1364 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |