题目

思路：

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define fi first
#define se second
#define lson p << 1
#define rson p << 1 | 1
const int maxn = 1e6 + 5, inf = 1e18, maxm = 4e4 + 5;
const int mod = 1e9 + 7;
// const int mod = 998244353;
const int N = 1e5;
// int a[505][5005];
// bool vis[505][505];
// char s[505][505];
int a[maxn], b[maxn];
int vis[maxn];
string s;
int n, m;

struct Node{
    int val, id;
    bool operator<(const Node &u)const{
        return val < u.val;
    }
}c[maxn];

int ans[maxn], pre[maxn];
int p[maxn], q[maxn];

void solve(){
    int res = 0;
    // int q, k;
    int x;
    cin >> n;
    for(int i = 1; i <= n; i++){
        vis[i] = 0;//vis下标
    }
    for(int i = 1; i <= n; i++){
        cin >> a[i];
    }
    int cnt = n;
    for(int i = 1; i <= n; i++){
        if(!vis[i]){
            int j = i;
            cnt--;
            while(!vis[j]){
                vis[j] = i;
                j = a[j];
            }
        }
    }
    bool flag = 0;
    for(int i = 2; i <= n; i++){
        if(vis[i - 1] == vis[i]){
            flag = 1;
        }
    }
    if(flag){
        res = cnt - 1;
    }
    else{
        res = cnt + 1;
    }
    cout << res << '\n';
}
    
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);

    int T = 1;
    cin >> T;
    while (T--)
    {
        solve();
    }
    return 0;
}