import 'package:test/test.dart';
int sum(List<int> numbers) {
int sum = 0;
for (int i = 0; i < numbers.length; i++) {
sum += numbers[i];
}
return sum;
}
int pivotIndex(List<int> nums) {
int leftSum = 0;
int arraySum = sum(nums);
for (int i = 0; i < nums.length; ++i) {
if (leftSum == arraySum - leftSum - nums[i]) {
return i;
}
leftSum += nums[i];
}
return -1;
}
void main() {
test('test case 1', () => expect(pivotIndex([1, 7, 3, 6, 5, 6]), 3));
test('test case 2', () => expect(pivotIndex([2, 1, -1]), 0));
test('test case 3', () => expect(pivotIndex([1, 2, 3]), -1));
}