寻找数组的中心索引

https://leetcode.cn/problems/find-the-middle-index-in-array/submissions/

前缀和

真妙！

public static int pivotIndex(int[] nums) {
    int sum = 0;
    int lSum = 0;
    for (int i = 0; i < nums.length; i++) {
        sum += nums[i];
    }
    for (int i = 0; i < nums.length; i++) {
        if (lSum * 2 + nums[i] == sum)
            return i;
        lSum += nums[i];
    }
    return -1;
}