1945C - Left and Right Houses - CodeForces Solution

import math
from collections import *
for _ in range(int(input())):
  n=int(input())
  l=list(input())
  dic={}
  x=Counter(l)
  a=0
  tt=[]
  for i in range(0,len(l)+1):
    if(a>=i/2 and x['1']>=(n-i)/2):
                  tt.append(i)
    if(i<n):
      if(l[i]=='0'):
        a+=1
      x[l[i]]-=1
  ans=-1
  for i in tt:
    if ans==-1:
      ans=i
    else:
      if(abs(n/2-i)<abs(n/2-ans)):
        ans=i

  print(ans)