1. Count: It is a mathematical behavior of repeatedly adding (or subtracting) 1. It is usually used to calculate how many objects there are or to place any number of objects (count the first object from the beginning, and correspond the remaining objects with natural numbers starting from two).

2. Sorting: The process of arranging unordered data elements in keyword order by a certain method is called sorting.

3. Measurement is to describe the observed phenomena with data according to certain laws, that is, to describe things quantitatively. Measurement is the quantization process of non-quantized objects.

4. Marking: mark the item with serial number (press 1, 2, 3, 4, 5, 6, ... . . Standard) order, make the items, articles more clear, won't make people look troublesome.

Extended data

Count:

1. The principle of classified addition counting

There are n ways to accomplish one thing, and there are 1 ways.

There are two different methods, and there are two of them.

There are two different methods in the N-type method.

There are three different ways to achieve this: * * *:

Different methods.

2. The principle of step multiplication and counting

To accomplish one thing, it needs to be divided into n steps. Step 1 includes

There are two different methods in the second step.

Different methods _ _, do the n step are

Different ways, then there is * * * to complete it.

Different methods.

Classification principle

It is known that a group of out-of-order data a[ 1], a[2] and a[n] need to be arranged in ascending order. First, compare the values of a[ 1] and a[2]. If a[ 1] is greater than a[2], the values of the two are exchanged, otherwise they remain unchanged. Then compare the values of a[2] and a[3]. If a[2] is greater than a[3], the values of the two are exchanged, otherwise they remain unchanged. Then compare a[3] and a[4], and so on, and finally compare the values of a[n- 1] and a[n].

After a round of such processing, the value of a[n] must be the largest in this set of data. If a[ 1]~a[n- 1] is repeated in the same way, the value of a[n- 1] must be the largest among a[ 1]~a[n- 1]. Then a[ 1]~a[n-2] are processed for one round, and so on. * * * After processing n- 1, a[ 1], a[2] and a[n] are arranged in ascending order.

Descending sort is similar to ascending sort. If a[ 1] is less than a[2], the values of the two are exchanged, otherwise they remain unchanged, and so on. Generally speaking, the maximum (or minimum) number will move to the end of the data sequence after each sorting round, and theoretically there will always be n(n- 1)/2 exchanges.

Reference: Baidu Encyclopedia-Inventory

References:

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