Sweet and Sour Rock

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#include<bits/stdc++.h>
#define ll          long long
#define pb          push_back
#define endl        '\n'
#define pii         pair<ll int,ll int>
#define vi          vector<ll int>
#define all(a)      (a).begin(),(a).end()
#define F           first
#define S           second
#define sz(x)       (ll int)x.size()
#define hell        1000000007
#define rep(i,a,b)  for(ll int i=a;i<b;i++)
#define lbnd        lower_bound
#define ubnd        upper_bound
#define bs          binary_search
#define mp          make_pair
using namespace std;

#define N  100005

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int TESTS=1;
    cin>>TESTS;
    while(TESTS--)
    {
        ll n;
        string s;
        cin>>n;
        cin>>s;
        vi dp(n+1);
        ll sum=0,mx=0,mn=0;
        dp[0]=0;
        rep(i,0,n)
        {
            if(s[i]=='0')
                sum--;
            else
                sum++;
            dp[i+1]=sum;
            if(sum>mx)
                mx=sum;
            if(sum<mn)
                mn=sum;
        }
        if(mn>=0)
        {
            cout<<n<<endl;
            continue;
        }
        vi vdp(mx-mn+1,-2);
        for(ll i=n;i>=0;i--)
        {
            if(vdp[dp[i]-mn]==-2)
                vdp[dp[i]-mn]=i;
        }
        ll fd=-1;
        for(ll i=mx-mn;i>=0;i--)
        {
            if(vdp[i]>fd)
                fd=vdp[i];
            vdp[i]=fd;
        }
        // rep(i,0,mx-mn+1)
        // cout<<vdp[i]<<" ";
        // cout<<endl;
        ll val=0,i=0,ref,ans=0;
        for(i=0;i<=n;i++)
        {
            val=dp[i];
            // if(val==mx)
            // {
            //  continue;
            // }
            ref=vdp[val+1-mn];
            if(ref>i)
            {
                ans+=ref-i;
                i=ref;
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}