# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
808009 | OrazB | Gondola (IOI14_gondola) | C++14 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
// #include "gondola.h"
using namespace std;
#define all(x) (x).begin(), (x).end()
#define ll long long int
#define pii pair <int, int>
#define pb push_back
#define ff first
#define ss second
const int N = 1e5+5;
int T[N];
// int replacementSeq[N];
int valid(int n, int A[]){
map<int,int> mp;
int pos = -1;
for (int i = 0; i < n; i++){
if (mp[A[i]]++) return 0;
if (A[i] <= n){pos = i;break;}
}
if (pos == -1) return 1;
int x = A[pos];
for (int i = pos; i < n; i++){
if (i > pos and mp[A[i]]++) return 0;
if (A[i] <= n and A[i] != x) return 0;
x++;
if (x == n+1) x = 1;
}
return 1;
}
int replacement(int n, int A[], int replacementSeq[]){
int x = valid(n, A);
for (int i = 0; i < n; i++){
T[i] = i+1;
}
int pos = -1;
for (int i = 0; i < n; i++){
if (A[i] <= n){pos = i;break;}
}
if (pos != -1){
int x = A[pos];
for (int i = pos; i >= 0; i--){
T[i] = x;
x--;
if (!x) x = n;
}
x = A[pos];
for (int i = pos; i < n; i++){
T[i] = x;
x++;
if (x == n+1) x = 1;
}
}
int mx = 0, ind = 0;
map <int,int> idx;
for (int i = 0; i < n; i++){
idx[A[i]] = i+1;
if (mx < A[i]){
mx = A[i];
ind = i;
}
}
for (int i = n+1; i <= mx; i++){
if (idx[i]){
replacementSeq[i-n-1] = T[idx[i]-1];
}else{
replacementSeq[i-n-1] = T[ind];
T[ind] = i;
}
}
return mx-n;
}
int countReplacement(int n, int A[]){
int x = valid(n, A);
if (!x) return 0;
const int mod = 1e9+7;
map<int,int>idx;
int mx = 0, ans = 1, cnt = 0;
for (int i = 0; i < n; i++){
if (A[i] > n){
idx[A[i]] = 1;
cnt++;
}
mx = max(mx, A[i]);
}
int num = 0;
for (int i = n+1; i <= mx; i++){
if (!idx[i]){
ans = (ans*1ll*cnt)%mod;
num++;
// cnt++;
}else{
ans = (ans*1ll*num)%mod;
cnt--;
// cnt -= 2;
}
}
return ans;
}
int main ()
{
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
int A[n];
for (int i = 0; i < n; i++) cin >> A[i];
// int m = replacement(n, A, replacementSeq);
// for (int i = 0; i < m; i++) cout << replacementSeq[i] << " ";
cout << countReplacement(n, A);
}