Longest Span with same Sum in two Binary arrays

#include<bits/stdc++.h>
using namespace std;

int main() {
	int t;
	cin >> t;
	while (t--) {
		int n, max = 0, curr, idx, len, s1 = 0, s2 = 0;
		cin >> n;
		bool a1[n], a2[n];
		int diff[2 * n + 1];
		memset(diff, -1, sizeof(diff));
		for (int i = 0; i < n; i++) {
			cin >> a1[i];
		}
		for (int i = 0; i < n; i++) {
			cin >> a2[i];
		}
		for (int i = 0; i < n ; i++) {
			s1 += a1[i];
			s2 += a2[i];
			curr = s1 - s2;
			idx = n + curr;
			if (curr == 0) {
				max = i + 1;
			}
			else if (diff[idx] == -1) {
				diff[idx] = i;
			}
			else {
				len = i - diff[idx];
				if (len > max) {
					max = len;
				}
			}
		}
		cout << max << endl;
	}
	return 0;
}