The thinking mode of the algorithm

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1. Counting

The chess board consists of a horizontal longitudinal 19*19 line, and How many squares are the lines composed of?



Solution 1: A number of one, side length of 1, edge length of 2, ...., side length is 18, so there are 1^2 + 2^2 + ... + 18^18.
Solution 2: Count the number of squares with a certain point as the lower right corner, this is too troublesome ...

2. Logical reasoning
The emperor was not poor, and among the miser there were poor, so some _______ were not _______.



Solution:

② some Scrooge was poor

① the poor are not emperors ==> some Scrooge is not the emperor.

3. Maximum contiguous Subarray
Given an array a[0,..., n-1], a continuous subarray of a, making the subarray and maximum.
? For example
? Arrays: 1,-2, 3, 10,-4, 7, 2,-5,
? Maximum sub-arrays: 3, 10,-4, 7, 2

The thinking mode of the algorithm