class Solution {
    public int pivotIndex(int[] nums) {
        int[] leftRight = new int[nums.length]; 
        int[] rightLeft = new int[nums.length]; 
        
        for(int i=nums.length-1; i>-1; i--) {
            if(i==nums.length-1) {
                rightLeft[i] = nums[i];
                continue;
            }
            rightLeft[i] = nums[i] + rightLeft[i+1];
        }
        
        for(int i=0; i<nums.length; i++) {
            if(i==0) {
                leftRight[i] = nums[i];
                continue;
            }
            leftRight[i] = nums[i] + leftRight[i-1];
        }
        
        for(int i=0; i<nums.length; i++) {
            int right = 0;
            int left = 0;
            if(i>0) {
                left = leftRight[i-1];
            }
            if(i<nums.length-1) {
                right = rightLeft[i+1];
            }
            if(left == right) {
                return i;
            }
        }
        return -1;
    }
}