import 'package:test/test.dart';

// Leetcode problem URL: https://leetcode.com/problems/find-pivot-index/

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));

}