1396 还是01串

#include<iostream>
#include<string>
using namespace std;
const int MAXN = 1000000 + 10;
int cntOne[MAXN], cntZero[MAXN];
int main(){
	ios::sync_with_stdio(false);
	string s;
	cin >> s;
	
	for(int i = 0; i < s.length(); ++i){
		if(i == 0){
			if(s[0] == '0')	cntZero[0] = 1;
			else cntOne[0] = 1;
			continue;
		}
		cntZero[i] = cntZero[i - 1];
		cntOne[i] = cntOne[i - 1];
		if(s[i] == '0')	cntZero[i]++;
		else cntOne[i]++;
	}
	int flag = 0;
	for(int i = 0; i <= s.length(); ++i){
		if(cntZero[i - 1] == cntOne[s.length() - 1] - cntOne[i - 1]){
			flag = 1;
			cout << i << endl;
			break;
		}
	}
	if(flag == 0)	printf("-1\n");
	return 0; 
}