剑指 Offer II 012. 左右两边子数组的和相等

剑指 Offer II 012. 左右两边子数组的和相等

var pivotIndex = function (nums) {
    var add = nums.reduce(function (acc, item) {
        return acc += item
    }, 0)
    var sum = 0;
    for (var i = 0; i < nums.length; i++) {
        if (add == nums[i] + 2 * sum) return i
        sum += nums[i]
    }
    return -1
};