Codeforces._NeW.c

#include <bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std; 
#define all(v) v.begin(),v.end()
#define allr(v) v.rbegin(),v.rend()
typedef vector<int> vi;
#define cl clear
#define stt string 
#define ll  long long 
#define ed end
#define vec vector
#define sz(a) int((a).size())
#define pp pop_back
#define minii min_element
#define maxii max_element
#define rv reverse
#define em empty
#define fd find
#define fr front
#define bg begin
#define bk back 
#define ppf pop_front
#define ppb pop_back
#define up upper_bound
#define lb lower_bound
#define no_cnt log10
#define pu push
#define in insert
#define er erase
#define pb push_back
#define accu accumulate
#define ff first
#define ss second
#define nl '\n' 
void solve(){
      int n;
        cin >> n;
        vi a(n);
        for(auto&x: a) cin >> x;
        vi b(n, 0);
        vi maxi(n, 0);
        b[0] = 1;
        maxi[0] = b[0];
        for(ll i = 1; i < n; i++){
            
            b[i] = b[i-1];
            if(a[i] > b[i-1]) b[i]++;
            if(a[i] < b[i-1]) b[i]--;
            maxi[i] = max(maxi[i-1], b[i]);
        }
        vi  dp(n, 0);
        dp[0] = 1;
        
        for(int i = 1; i < n;  i++){
            dp[i] = dp[i-1];
            if(dp[i-1] < a[i]){
                dp[i] = dp[i-1] + 1;
            }
            
            if(dp[i-1] > a[i]){
                dp[i] = maxi[i];
                if(a[i] > dp[i]){
                    dp[i]++;
                }
                dp[i] = max(dp[i], dp[i-1] - 1);
            }
        }
        ll ans = min(dp[n-1] , n-1);
        cout << ans << nl;
}
int  main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
 // freopen("input.txt", "r",stdin);
 // freopen("output.txt", "w",stdout);
    ll t;
    cin >> t;
    while(t--){
    solve();
    }
    return 0;
}