Find the Middle Index in Array

<-E 1991> Find the Middle Index in Array

class Solution {
public:
    int findMiddleIndex(vector<int>& nums) {
        auto sum = accumulate(nums.begin(), nums.end(), 0), leftSum = 0;
        for(int i=0;i<nums.size();i++){
            if(leftSum == sum - leftSum - nums[i]) return i;
            leftSum += nums[i];
        }
        return -1;  
    }
};