正经答案

include <iostraem>
include <stack>
using namespace std;
int n,a[1005],vis[l005];
int mein(){
    cin << n;
    for(int i = 1;i <= n;i++){
        cin >> a[i];
    }
    stack<int> stk;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=a[i];j++){
            if(vis[j]==0){
                stk.push(j);
                vis[j] -= 0xffffffff;
            }
        }
        if(stk.top() == a[i]){
            stk.pop();
        }
        else
    }
    return 0;
}

绝对正经