9.19 array bubbling sorting and dichotomy

Arrays: Collections of data of the same type

Strongly typed language: 1, the array can only hold data of the same data type.

2, you need to define the length of the array (can hold the number of elements)

Collection: 1, can store any type of data,

2, the definition of time does not need to set the length

3, memory space is not contiguous

Js

Array: 1, which can hold any type of data.

2, the definition of time does not need to set the length

Defines an array of var attr = array (1,3.14, "AA"); The data in the array is arranged in order 0 1 2 3 4 ...

Each data in the middle is separated by commas,

Var attr= attr (5);

Var attr=[1,3.14, "AA"] defines the output directly with square brackets.

Alert (attr[2]);

Property

length is the array length,

Alert (attr.length); Output array length,

Push Append Element

Attr.push ("BB"); is to add BB to the attr number set,

Array traversal

for (Var i=0;i<attr.length;i++)

{

Alert (Attr[i]);

}

foreach () Way Traversal a is an index.

For (Var a in attr)

{

Alert (Attr[a]);

}

Example

Ten scores, total score, highest score, lowest score

var attr =[89,80,76,49,90,25,85,76,59,40];

var sum = 0;

for (Var i=0;i<attr.length;i++)

{

Sum + = Attr[i];

}

alert (sum); Sum of results

var ZG = 0;

for (Var i=0;i<attr.length;i++)

{

if (ATTR[I]>ZG)

{

ZG = Attr[i];

}

}

alert (ZG); highest score

var zd = ZG;

for (Var i=0;i<attr.length;i++)

{

if (ATTR[I]<ZD)

{

ZD = Attr[i];

}

}

alert (ZD); Minimum score.

Add to Weight

var attr = [2,5,10,16,27];

var sj = 27;

var CF = true;

for (var i=0; i<attr.length;i++)

{

if (SJ = = Attr[i])

{

CF = false;

Break

}

}

if (CF)

{

Attr.push (SJ);

alert (attr.length);

}

Else

{

Alert ("With duplicate value");

}

var attr = [1,8,26,4,15,3,7,42,9];

sorting An array element

Bubble sort

8 6 4 5 3 7 2 9 1 8

8 6 5 4 7 3 9 2 1 7

8 6 5 7 4 9 3 2 1 6

8 6 7 5 9 4 3 2 1 5

8 7 6 9 5 4 3 2 1 4

8 7 9 6 5 4 3 2 1 3

8 9 7 6 5 4 3 2 1 2

9 8 7 6 5 4 3 2 1 1

Two adjacent elements are compared to meet the conditional element interchange

The number of wheels to compare is the length of the array minus one

Define an intermediate variable used by an interchange

var zj = 0;

Control the number of wheels to compare

for (Var i=0;i<attr.length-1;i++)

{

Control the number of comparisons per round

for (Var j=0;j<attr.length-1-i;j++)

{

If the next element is greater than the current element

if (attr[j]<attr[j+1])

{

ZJ = Attr[j]; Swap

ATTR[J] = attr[j+1];

ATTR[J+1] = ZJ;

}

}

}

Alert (attr[0]);

Attr.sort ();

Alert (attr[3]);

Find data inside an array

var attr = [1,2,3,4,5,6,7,8,9];

The value to find

var v = 0;

How loops are traversed

var sy =-1;

for (Var i=0;i<attr.length;i++)

{

if (ATTR[I]==V)

{

sy = i;

}

}

if (sy = =-1)

{

Alert ("No data Found");

}

Else

{

Alert ("The data is indexed inside the array:" +sy);

}

Finding data by dichotomy

Minimum index

var minsy = 0;

var maxsy = attr.length-1;

var Midsy;

Cycle comparison

while (true)

{

Calculate Intermediate Index

Midsy = parseint ((minsy+maxsy)/2);

Compare intermediate values and user values

Determines whether the value of the intermediate index equals the value that the user is looking for

if (attr[midsy] = = v)

{

If it's equal, exit the loop and find the data

Break

}

Determine if there are only two of data left

if (Midsy = = Minsy)

{

Determine if another two data is equal to the value that the user is looking for

if (ATTR[MIDSY+1]==V)

{

The value is found, exiting the loop

Midsy = midsy+1;

Break

}

Else

{

No value found, exit loop

Midsy =-1;

Break

}

}

To change the range.

if (ATTR[MIDSY]>V)

{

Maxsy = Midsy;

}

Else

{

Minsy = Midsy;

}

}

alert (MIDSY);

9.19 array bubbling sorting and dichotomy