寻找数组的中心下标

/*
 * Problem: Find the pivot index using Java Streams.
 * Approach:
 * 1. Calculate the total sum of the array using streams.
 * 2. Iterate through the array, maintaining a running left sum.
 * 3. For each element, check if the left sum equals the total sum minus the left sum minus the element.
 * 4. If such an element is found, return its index; otherwise, return -1.
 */
import java.util.stream.IntStream;
public class Solution {
    public int pivotIndex(int[] nums) {
        int totalSum = IntStream.of(nums).sum();
        int leftSum = 0;
        for (int i = 0; i < nums.length; i++) {
            if (leftSum == totalSum - leftSum - nums[i]) {
                return i;
            }
            leftSum += nums[i];
        }
        return -1;
    }
}