编程比赛程序题英文，编程比赛试题

Here is a programming competition-style problem statement in English:

Problem: Maximum Subarray Sum

Given an array of integers, find the maximum possible sum of a contiguous subarray within the array. A subarray is defined as a sequence of consecutive elements within the array.

Input:

- An array of integersarr with lengthn, wheren is a positive integer andarr[i] is an integer.

Output:

- A single integer representing the maximum sum of a contiguous subarray.

Constraints:

1 ≤ n ≤ 10^5

-10^9 ≤ arr[i] ≤ 10^9

Example 1:

Input:arr = [-2, 1, -3, 4, -1, 2, 1, -5, 4]

Output:6

Explanation: The maximum sum is obtained by summing the subarray[4, -1, 2, 1], which gives a sum of6.

Example 2:

Input:arr = [1]

Output:1

Explanation: The maximum sum is simply the single element in the array.

Example 3:

Input:arr = [5, -3, 5]

Output:10

Explanation: The maximum sum is obtained by summing the subarray[5, -3, 5], which gives a sum of10.

This problem is a classic example of the Kadane's algorithm, which is used to find the maximum sum of a contiguous subarray within a one-dimensional array of numbers. The algorithm works by iterating through the array and at each step, it decides whether to continue the current subarray or start a new one. The maximum sum found during the iteration is returned as the result.