2574. Left and Right Sum Differences

Given a 0-indexed integer array nums, find a 0-indexed integer array answer where:

• answer.length == nums.length.
• answer[i] = |leftSum[i] - rightSum[i]|.

Where:

• leftSum[i] is the sum of elements to the left of the index i in the array nums. If there is no such element, leftSum[i] = 0.
• rightSum[i] is the sum of elements to the right of the index i in the array nums. If there is no such element, rightSum[i] = 0.

Return the array answer.

class Solution {
public:
    vector<int> leftRigthDifference(vector<int>& nums) {
        int n = nums.size();
        vector<int> l(n), r(n);
        for(int i = 1; i < n; i++) {
            l[i] = l[i-1] + nums[i-1];
        }
        for(int i = n - 2; i >= 0; i--) {
            r[i] = r[i+1] + nums[i+1];
        }
        vector<int> res(n);
        for(int i = 0; i < n; i++) {
            res[i] = abs(l[i]-r[i]);
        }
        return res;
    }
};