请教contiguous subarray的概念及指定示例的判定依据

Hey there! Let me break this down for you clearly.

First, let's nail down the basic concept:
A contiguous subarray (or continuous subarray) is just a sequence of elements from the original array where all elements are adjacent with no gaps. You can't skip elements when picking a contiguous subarray.

For example:

• From your array [-2,1,-3,4,-1,2,1,-5,4], [1,-3,4] is a valid contiguous subarray (they sit next to each other in the original array).
• But [-2,4,2] is NOT contiguous — those elements aren't adjacent in the original array, so you can't form a contiguous subarray with them.

The subarray [4,-1,2,1] you're seeing is the maximum sum contiguous subarray for the given array. This is a classic example from the well-known "Maximum Subarray Problem" (often solved with Kadane's algorithm). Let's verify this:

1. Calculate its sum: 4 + (-1) + 2 + 1 = 6
2. Compare with other possible subarrays to see why this is the largest:
   • Sum of the entire array: -2 + 1 - 3 + 4 -1 +2 +1 -5 +4 = 0, which is way smaller than 6.
   • The subarray [4] sums to 4, still less than 6.
   • [2,1,-5,4] sums to 2, not close to 6.
   • Even the longer subarray [1,-3,4,-1,2,1] only sums to 4, which is still less than 6.

So the reason this specific contiguous subarray is called out is because it's the one that gives the highest possible sum out of all possible contiguous subarrays in the original array.

内容的提问来源于stack exchange，提问作者Sushil Shinde