Calculating Subarray Sum Using Prefix Sum In O(1) Time Complexity

Problem
TC: O(n) for calculating the prefix sum and O(1) for getting the sum of the subarray in the range left and right

class NumArray {
    int prefix[];
    public NumArray(int[] nums) {
        prefix = new int[nums.length];
        int currentSum =0;
        for(int i=0;i<nums.length;i++){
            currentSum+=nums[i];
            prefix[i] = currentSum;
        }
    }
    public int sumRange(int left, int right) {
        int rightSum = prefix[right];
        int leftSum = (left>0) ? prefix[left-1]:0;
        return rightSum-leftSum;
    }
}
/**
 * Your NumArray object will be insta...