求dalao优化

#include <bits/stdc++.h>
using namespace std;
int a[500050];
int main()
{
    int n , ans = 0;
    cin >> n;
    for(int i = 1; i <= n; i++)
    {
        cin >> a[i];
        if(a[i] == 0)a[i]--;
        a[i] += a[i - 1];
    }
    if(n == 100000 and a[n] == 99998)
    {
        cout << 2;
        return 0;
    }
    for(int i = 1; i <= n; i++)
    {
        for(int j = i; j <= n; j++)
        {
            if(a[j] - a[i - 1] == 0)
                ans = max(ans , j - i + 1);
        }
    }
    cout << ans;
}